Okay, now that I found everything in the Toybox, I'll write down my thoughts:
I really enjoyed playing the Toybox. The animations and the controls feel pretty polished, so I guess there won't be any major changes until the final game releases.
The level design was pretty neat, and you really need to explore every part of the level if you want to collect that pagie (and I'm pretty sure everyone's trying to get it at one point).
I also really liked that you can invert the game's camera. I'm pretty used to the A Hat in Time control settings, that's why this was a useful feature to me. Hopefully they're going to add more control settings to the final game; if that's the case, I might change the underwater controls, since I'm not that happy with the current ones.
The "roll" move (Is there a proper name for this move already?!) still felt a bit "floaty", but maybe that's just me still getting used to the game's controls.
I found myself accidently falling off several green platforms, because I couldn't see the edge. That's due to the simple color scheme in the Toybox, but it won't be any problem in the final game, since the final worlds are having a more detailed art style.
I'm really glad that Playtonic added that blob shadow to the game; I couldn't imagine playing this level without this feature...
The particle room at the end was a nice addition to the game. Can't wait to see these effects in the final game.
That's just my two cents on the regular Toybox. I'm looking forward to seeing what the Toybox+ is all about!