The angled jump mechanics are very weird to play with, and don't work very well for precise jumps, making it somewhat difficult to progress. (And I cannot for the life of me figure out how to get up to the second checkpoint, or figure out how to make any progress in the room with the red enemies..)
Mechanics aside, I think that the game would benefit from having more visually interesting environments. (Although that's more of a finishing touch.)
So far it's a very promising game, it just needs a bit of work. The character animations are very cute as well! I'll be sure to follow for updates. ^^