I like everything about this. The jumping mechanic is a great idea, and the level design uses it well. There are some challenging parts, but the frequent checkpoints keep everything moving nicely. I was sort of hoping for a boss at the end, but the difficult end of level 10 is a good substitute. Unfortunately, I had some slowdown issues during that part for some reason, although the rest of the game was fine. I don't see anyone else mentioning it though, so it's probably on my end. I played the game in Google Chrome, just fyi in case someone else has the same problem.
My only real complaint is that I wish it was longer. I hope you're considering making a sequel.