Finished the sandbox and I believe I saw all the secrets.
animations are better than I expected. The feel of the controls are better than I expected. It's not weighty like Banjo Kazooie or Mario 64 was, or even modern day Mario. But there's enough inertia there that jumping and moving around feels good all around. being a modern 3D platformer at 60FPS on PC, the camera, controls and everything feel a bit effortless. In many Mario games, climbing something has a small feeling of satisfaction, but in Yooka Laylee it feels like you have more than enough tools at your disposal to manage it without much thought.
I think Playtonic knows that and some of the challenges and designs in their toybox show that they have a grasp on the Unity engine and how their game is going to work. There are some really cool secrets that they hide in some devious spots. Some of the quills you collect have methods that rely on your knowledge of the sandbox and the physics and less on Playtonic trying to lead you into a certain way of grabbing it. There's an large amount of high flying platforms and and the scale of the entire sandbox is large to compensate for how quickly and easily Yooka-Laylee can bop around.
The writing is also funny and charming and the little robot that guides you through the toybox had me laughing a bit. I think my kickstarter money is well spent. Feel MUCH better about the state of the game.