It was ambitious, but ultimately mediocre in my eyes.
If they were trying to attract new players, I hope the vehicle creation wasn't aimed at the kiddies. Despite the building process being user friendly, the physics do everything in its power to make sure you account for every single variable a vehicle has to offer. It's not accessible, and it's also not very fun unless you get extremely attached to your vehicle and tweek it for an obscene amount of time. And even then, it is very likely to end up being a massive heap of junk compared to even the default vehicles. Wheel spacing, where weight is distributed, the power source and where it's placed, and whether your vehicle can even handle curbs or crashes without falling apart--it gives the whole process a learning curve that had no business being so demanding.
Those who put in the time might want to accuse me of not fully utilizing the physics. Well I sure might have been tempted to if an excessive chunk of those challenges were anything but repetitive, mindless or frustrating. Even if it wasn't Banjo 3, I still went into this excited to put my vehicle ideas to the test. I remember being in the creator more than the game itself, because I told myself over and over that there was no way what I felt--the feeling of fighting the game engine--was what the creators intended in these challenges. Almost none of them felt great to beat in any of the vehicles I tried, and going from one to the next back to back in these empty barren worlds eventually had me feeling like I was performing chores. The hell with heavy or weak vehicles, the hell with vehicle combat, and the hell with worthless worlds. Also, Banjo's new look is nowhere near as endearing.
As for the good:
It had insane presentation value. The opening, minus the controversial LOG line, was charming, nostalgic and incredibly polished. Spiral Mountain looked incredible (I was dying to explore it), as did the rest of the game. I bet its aged really well. The lighting, scale and art direction were truly next-level.
Also, classic Rare-humor was present in the dialogue without feeling (from what I remember) forced. And after getting over the disappointment from leaving Spiral Mountain, I was excited to explore the rich world of Showdown Town. It was full of detail and, for the briefest of moments, you could almost feel like you were exploring a platfomer's world. And messing with cops was neat.
The best thing about the game though is the godly music. The Terranium has some of my favorite tracks. It's some really great stuff, and I actively listen to it years after dropping the game.