Finally beat it! Normal mode, that is. I don't even wanna try the hard ones. But it was pretty fun, and the art style and the concept are great. I have some problems with the gameplay, though: Because there's no visual or audio feedback when you get hit, it's pretty hard to get used to the hitbox. Also, when you jump, the speed counter goes off screen, and that killed me a lot. I would also like to have some indication that you're slowing down, like a different animation, or the character starting to wobble, or something like that.
Oh, and (this isn't part of the review, just an idea I had while playing) what if instead of pressing R, you had to quickly press the left and right keys to spin faster? Maybe that would add an interesting layer of challenge? I dunno.
Good job on the game!