I don't know if those are read but I would like to cover some things that haven't been mentioned here (or not enough).
First things first, I really enjoyed the game. It brought me back in my young days when I received a copy of Banjo-Kazooie on Christmas, one of the games of the N64 era I spent the most time on. So just thank you, Playtonic games, for this.
However, on the long run, the experience went downhill and I think some things could be improved. This can be a good thing for a potential second game to be aware of this. I'm not a game designer, just a player, so maybe some of these doesn't really fit with the reality, but here are my two cents =).
Theming is more than random doodads drops
In Banjo-Kazooie (& Tooie), one of the main theme was the puzzles. We collect jiggies, but it doesn't just stop there : to open a world, we need to complete a puzzle (it was done automatically in B-K, but B-T even included a mini-game, which also was a "bonus game" in B-K). Of course, jiggies are also mentionned or drawn, but this doesn't influence the gameplay. And, even if the "B-K" version didn't have a proper gameplay, it was funny for younger-me to watch the pieces fill, one by one, the puzzle, when I pressed A. Opening a world had this little thing that made it unique.
I didn't really found this in Yooka-Laylee. Opening a world was just opening another book with the same cutscene. I really think something better could have been done. We collect "pagies", but was this a really good idea in the first place ? A jigsaw piece is something unique in a puzzle, so it feels important. A page seems more generic, so it wasn't really the same for me. There are 25 pagies per world, what about adding one and collect letters instead ? And, to "open a book", how about a minigame with the letters ? Like a hangman/wheel of fortune minigame where the player have to find out the title of the book ? It would add more meaning to the theme.
Also, what is that "expend the book" feature ? I mean, it's cool to open new areas of existing levels, but I didn't really get what it had to do with the "book" theme in the first place. Also, being able to expend a world I never went in was a bit frustrating : I know I have to expend it, but I first want to see what is inside the "not-expended" world, even if I know it is just a waste of time ! I didn't really get that part... We are in a book, right ? What about telling the player a story ? Imagine we meet the book's hero that needs to fight the book's villain. We can gather pagies (or letteries ?) with side quests/exploration, but we can also help the "book hero" to progress. With that setup, parts of a level are chapters of the book that appears with the progression of the main quest and reveals more of the book's story. What about a hero that needs to rescue a princess in the Glitterglaze Glacier castle, and we help him to do so ? Or a hero that we follow during the story, but, in the final chapter, we discover that he's, in fact, the villain ? This could have brought more emphasis on the "book" theme and add more uniqueness to the levels, even beyond B-K and B-T, instead of just droping books and letters here and there.
I mean, if the main theme of the game doesn't influence the gameplay, even just a little bit, your theme is more a "skin" than a real theme. In Yooka-Laylee, without changing a line of code, if you change the visual models of the decorative books in the hive, the random letters doodads and the pagies by decorative instruments, random notes and musical sheets, you have a musical-themed game with a villain that wants to steal all the music in the world. No part of the gameplay would change. If you even change the cutscene of the book opening, you could literally do any theme you want. You can't do this as simply with B-T due to the "jigsaw" minigames (and you can barely do it with B-K due to the piece-by-piece animations that you can do to open a world).
Let the player choose the controls
This point have already been mentioned, but I have a bit more to say about it. I played Yooka-Laylee on PC (Steam version) with a keyboard/mouse layout, since I don't own a controller. Also, as you could have guessed with my kind-of approximate English, I'm not an English native speaker. That also mean that I use a different keyboard layout instead of the QWERTY one. That makes the game really difficult to play natively. It was not a real problem for me, since I also have installed a QWERTY keyboard layout and a simple keyboard shortcut allows me to switch between QWERTY and my native layout (alt + shift, note it, it will be important in 4 lines), but it could be harder for people that doesn't know how to do it. Personally, I just needed to explain to my girlfriend why does typing 'A' types 'Q' when I forgot to switch it back after playing.
But level 5 changed everything.
In level 5, you learn the Sonar Shield. And the shortcut for that move is... Yeah, you guessed it : Alt + shift. That means that everytime I use the Sonar Shield, my keyboard layout changes and I can't control my character properly, so I can't move. So I need to re-use it to get back to normal, but that cancels the move. Fortunately, there is no instance in the game where I need to move while activating the sonar shield, right ?
Of course, Playtonic can't think about all the keyboard layouts that exists, but a simple way to manage this would have been to allow us to choose which button does what ! A PC game that doesn't have this option is really rare. But, unfortunately for us and the Banjo-Kazooie franchise, rare doesn't always mean good.
Also, I know that Yooka-Laylee is a tribute to the N64 era. But there is ONE thing that I do not feel nostalgic about that time : the camera. The early 3D games had that atrocious camera that never knew were to put itself. Unfortunately, Yooka-Laylee also brought that back from the 98's. Everybody already noticed the unwanted camera changes, so I will just point one specific thing that I haven't seen on that thread : the camera rotation speed is way too slow, even with the fastest setting. If I want to look around with my mouse, I need to travel all the way from one side of my desk to the other side, I'm not even kidding.
Also, the "Not-so-subjective view", what is this ? Why couldn't we have a real first-person view to look around without having the half of the screen masked by our character ?
Not enough "Oh ! Okay, let's go !" moments
Yooka-Laylee is... Predictable. It nearly never surprise the player. Everybody mentioned the "race through the loops" that is a recurring theme, but it's not the only redundant part. Every level has a transformation, an arcade machine, races and loops, a boss, the snake-man that will sell us a move, one skeleton adventurer, the jinjos that I don't know the english name, an expansion, random NPCs without backstory... Once you've cleared the first level, you already know the content of the other levels.
Yeah, in Banjo-Kazooie, you didn't have a transformation in all the levels. That can look like a flaw, but it made the level a less predictable. Every level was like a surprise and you never knew what was inside. Will I transform in that level ? Will I learn a new move ? Is there a boss ?
In every level of B-K, there are many "Oh, okay, let's go" moment. Oh, there are four versions of the same level, each one defining a season, and I have to play with that ? Okay, let's go. Oh, there is a giant shark that is friendly and he needs my help ? Okay, let's go. Oh, there is a ending quiz about everything in the game ? Okay, let's go. Oh, activating that camel makes it appear in other levels ? AND EVEN IN OTHER GAMES ? OKAY, LET'S GO ! There are even more in B-T. In Yooka-Laylee, I had 2 of these moments so far, both in the casino level : one when I saw the knight piggies (Oh ! Those are the NPCs from the first level ! Okay, let's go !) and a BIG ONE at the end of the Kartos sequence of that level (Oh ! I HAVE TO FIGHT A BOSS DURING WITH THE KART ? OKAY, LET'S GO !). Except for these two things, the game never really surprised me after the first level.
Encountering new characters in a new level is normal, and encountering a character that is in all levels in a new level is also normal. What about developing some existing NPCs in some levels, and giving them some backstory ? I can't name a single NPC name of Yooka Laylee except Rextro and Kartos because we generally talk to them only once. I played BK when I was a kid, but I still remember Boggy, Gobi, Brentilda, Eyrie and a lot of others, because I saw them multiple times and I saw them evolve.
Also, every task in B-K, B-T had another reward with the jiggy. Something more. I remember when I saw Eyrie as an adult eagle after all the quest long quest to feed him, it felt SO GREAT ! Or when you helped Boggy aaaaaall the way, and finally, when you go back to its home each time, instead of the sad little music you hear the happy version with its children "yays". That was so cool ! I didn't find anything comparable in Y-L. Me, as a player, didn't really had any impact on the world. I saved that skeleton girl in the first level from being eaten ? Okay, cool, but... I couldn't even get her out of the cooking pot ! I got the hat back to all the snowmen and they didn't do anything. Aren't they supposed to do some kind of show ? Our only reward are pagies, we can't expect anything else.
Disputable gameplay mechanics
Why do we have a "stamina" bar ? I never found a place where I had to manage carefully my stamina in a puzzly fashion, just numerous "Damn, I have to wait again" moments. Ok, let's be fair, B-K and B-T started it first, and it was, in my opinion, even worse : instead of time, we had ammo (feathers, eggs...) and, if we hadn't enough, we had to search in aaaaaaaall the level (or even in other levels) some ammo and come back where we needed it. Fortunately, it nearly never happened to me due to the large stock of ammo you naturally made, but the few times it happened, it was infuriating. But the stamina bar was not the solution, or, at least, not like this. I understand that you need to limit the flight, but why limiting the "talon trot-rolling thing-whatever" ? I like going fast, it's not like this move is broken ! Is it because you can hit enemies with ? Well, prefer being hit and not using stamina for this ! Fights are anecdotic in Y-L, like they where in B-K and B-T, why limiting the character movement because of this ? Same for the sonar thingy and the sonar explosion. Why does this have to use stamina ? I literally used them only for their puzzles... Having to wait to be able to move or to do a puzzle isn't fun. The infinite-but-limited-in-time powerups, like the berries, are a better way to handle this, in my opinion.
Also, I disagree with everyone suggesting putting back the Flight Pads. I personally loved being able to fly everywhere in the world, that felt very good. It's an end-game power, of course it HAVE to be powerful. Maybe, however, it should have been obtained even further in the game, like a bonus gift for obtaining a lot of pagies, just to help to get the last ones.
The mini-games aren't really enjoyable. B-T started this one too, but Y-L minigames aren't really fun. Controls are clunky, they aren't hard, and you couldn't finish them early (it's mostly "do a lot of points in X minutes", I'm more of a "do X points in the fastest way possible" guy). But everybody covered that one, so I won't expand it.
The transformations are waaaaaay too scripted. Again, some transformations in B-K and B-T are also scripted (the pumpkin in B-K, for example), but in Y-L, it's ALL of them. For me, a transformation needs to be useful everywhere, and not only where the scripts tells it is. The Click-Clock Woods bee transformation allows you to fly everywhere, Jolly Roger's lagoon allow you to breath in water, Bubblegloop Swamp's crocodile allows you to not take damage in the swampy areas... They are "quality of life" transformations more than just scripted events in a restricted area. To be honest, Y-L Helicopter seemed really good at first glance, but I acquired the fly ability literally 2 minutes after my helicopter transformation, which killed it.
Can I roll on that thing ? And why did that hurt ?
This is a quick one, but the game doesn't tell me enough what I can/can't do. It's cool to have that red layer on invincible enemies or our characters, but I never could guess, when I looked at a slope, if I could walk on it, roll on it or if I needed the honey mutator. Icy slopes need honey, but sometimes not. Slopes sometimes need rolling, but the same (?) angled-slopes in another location doesn't. Is that all scripted with arbitrary triggers ?
Also, sometimes, during my exploration, I was randomly hit by some triggers without being warned first. First in the "cold cavern" then at some poisonous area. Nothing indicate that I'm entering a dangerous area, or I didn't notice. It's just "hey, you just touched an invisible trigger, so take some damage". I'm okay with taking damage in obviously poisoned water, but not when I'm following a path.
But... It's a great game !
After typing a longer-than-I-intended speech in probably bad English because midnight-me starts to be tired, I really want to finish on a positive note. Nothing is perfect, so, of course, this game has some flaws. But I really enjoy it. It's my childhood 20 years later, and the main things are here. This game, with all I said earlier, can be the foundations of a great new era of games that perfectly mix the good old games from my childhood with the current technologies and the contemporary knowledge of game-making.
I really hope that Y-L won't be the only try from Playtonic Games. Everything I said earlier was nothing but trying to be constructive, because I really want to see Playtonic Games get the success they deserve.
You guys are amazing, keep it up !