What's with the rating? It's pretty good to me.
But OK, looking back, I wasn't at all impressed at all the level design, but the fun lied in the power-ups for me. At first I didn't know that the shoulder buttons served a purpose in a racing game, because all I knew was that X was accelerate and Triangle was back. But once I got the hang of it, and the concept of combining three of the same power-ups, I really had a lot of fun! And you know what? That concept of combining three of the same power-ups thing is a concept I would like seen in a Mario Kart game, actually.
Other than that, the game is OK, and simply fun. Oh, and the cute characters are pretty much a bonus.