Fun little game!
It's got a great sense of speed, decent challenge, and interesting unlockables which gave me an incentive to keep playing. It's very satisfying to play this well.

Music and graphics also great. It's got a pleasant sense of style. I don't know what the limitations of the thing this was made in are, but I bet this is pretty impressive considering them.

My only gripes are:

• I wish the camera let me see where I was going more. I was frequently unable to see into the turn I was taking. It also made me feel a bit dizzy.
• I wish rings disappeared visually when used, making it clearer which rings are still active after a lap. I found myself trying to use spent rings and being confused when they didn't work.