This game should never have been released!
Don't get me wrong, I'm not bitter; Luckily I borrowed the game from a friend so wasn't unfortunate enough to have actually spent money on it.
It just seems like they never bothered to finish it. There are obvious glitches (such as an incomplete part of a track where you can fall through the ground into oblivion), the graphics are awful and fuzzy and the physics are jumpy. I can't describe it any better: it just feels like they said "I'm bored now, shove it in a box and let's go home".
I cannot urge you strongly enough not to spend money on this game, no matter how deep at the bottom of the bargain bin you find it.