Quite fun, and the art style is just fabulous. The mechanic is really cool and adds an extra layer to something that is relatively simple conceptually. I could honestly see it just taking some more levels to turn this into a full game, which is pretty freaking impressive for a jam if you ask me!
Definitely seemed pretty difficult to me personally, but I'm terrible at most games in the world so, might be my fault. I wonder if some platformer magic (things like coyote time and whatnot) might help with some of the difficulty; some of the jumps felt surprisingly finicky. But I don't know. Platformers are not my area of expertise.
Overall, these issues are very small and pretty subjective. In other words, this is an excellent entry!