Fantastic game! The art is nice, especially the derpy tongue as he jumps. The story was surprisingly touching, and I enjoyed the final boss fight (this as someone who generally dislikes bosses).
A few minor quibble about polish: there are spikes which you can fall onto without seeing them, the "coyote time" doesn't seem to work on moving platforms, and the dash cooldown isn't indicated in any way I could tell. As I say, minor problems. Overall, this was a really nice entry.
I liked the level design. It looped back on itself very nicely, and the checkpoints were much appreciated. That said, you could maybe be more generous with checkpoints early on, to help ease players in.
EDIT: And apparently there's a map screen? The level design was clear enough that I never found myself needing it.