There is too many reasons to hate i can't explain them all.
5 bucks you haven't even played the game and are just echoing everything you've read about it. Which is fine, except for the fact that it's 6 years dead now.
But I'll humor you anyway.
There is no AI and you can drive up vertical walls at full speed and clip through bridges and when you win (which you will always do because there is no AI coded for the other cars) you get a lovely trophy declaring "YOU'RE WINNER"
It came out over 6 years ago and it was featured in magazines, on the Internet, and even on TV as being the worst game ever made.
Apparently it's so horrible that people still want to talk about it 6 years later.