Holy cow, this is a really well done game!
The controls feel good, I like the arcade-y feel of the turns and the handbrake is a nice little addition for tight corners. The graphics look great with lots of bright colors and pixel goodness. The audio is well done, although I would say the default sound levels are a touch high.
My only real complaint is that the AI is not very good, so the game is really easy.
Overall very nice job!