Not too bad, but not too great either
I know that this is only a demo so please take this as a criticism. I like the graphics and the controls a lot as well as the simple concept. I would recommend (As I am sure will be different in the full version) to give a 'break' before the game starts with a map of the controls. I also think that the track should be a bit more open, in that you don't crash as soon as you touch the grass. I think that you are doing a really good job on it. Items would also be a plus, like speed bursts and etc... as well as people to play against (AI are fine). Also guns, cause guns never hurt in a game :-). Looks good so far, I'll be interested to see how this turns out.