This game is really pretty. The pixel art is gorgeous, and the sounds are very nice too. And of course the animated cutscenes.
The puzzles have a nice amount of variety without overstaying their welcome. The game is like, the perfect length for the number of mechanics in it.
And, the puzzle mechanics are good. It's kind of like, each puzzle is about assembling the right steps for a mini platforming stage, and then every component of the stage is timed... it's kind of a novel concept and works pretty well here.
I also like the split between the two paths in the level design. It seems like that requires making sure each path is comprehensible without having seen the other one, while also meaning that once you loop around to the other path, you have a better grasp of the mechanics and so can complete it more smoothly. Just kind of a cool feature.