The concept is really unique and makes for some interesting puzzles. I definitely liked the second world the best, being able to freely move the blocks made for much more player focused (not sure that's the right term I mean here?). In the sense that the player had more ability to control the puzzle/character.
But the final level, honestly made me more frustrated than satisfied. The book cases seemed to sometimes have janky collisions leading to a gap appearing causing the little guy to fall instead of walking across, and the fact the movement is dependent on the mouse position relative to the player makes standing on the thing that your moving cause the player to move which accelerates it movement making the vertical slides feel kinda janky. These issues wouldn't be as bad if the player had full control of the player but the fact you have to wait for the little guy to walk all the way back every time got annoying cause I felt like I was just waiting to be able to play again.
Overall though this is really good, even though that last level did annoy me, I think this is a really unique concept, and again the second level was very fun.