It's pretty good, controls are good, graphics are simple but effective, and music is good. But a big problem that gets very annoying after a while is how the music stops when you jump. This sounds like a small problem, but it gets very annoying very quickly.
Amazing concept. The only negative aspect to this game is the fact that the jumping is pretty hard to control. Try making it so that you can control trajectory mid-air with WASD and can control the speed and such with the mouse (as before).