This game is mint!
It's amazing. I could play it all day. I love the music, i love the little guy, and I love the simplicity. I don't too much like the way too simple and ugly menu, but that isn't too big of a deal - because once the game starts, the fun commences.
I'd work on some of the artwork. Maybe a couple features. Checkpoints, lives, possibly some animations for the character once he hits those finish lines, or eyes looking in the direction of travel. I'd also look at some of the glitches. Falling from a top ledge, onto a lower ledge, glitches, you bounce around - then just fall.
All in all though, sweet game. ^^