This is a cute game but it feels like it goes on for too long. There are some really clever ideas for puzzles/challenges but there's also a lot of filler in-between that just repeats them or does something much simpler than what came before it. By the time I got to 1-20 or so, I just wanted to get to the end (I eventually stopped at 33; wish it would tell you how many there are).
I liked the puzzles that did something new with the boxes. My favourites were using it to limit your jump height rather than to get higher up, the first door puzzle, and the (first) one with a door on a moving platform, which stumped me for a bit. Those felt good to figure out, I just wish it didn't repeat simple ideas so much.