My god, this is the best PSP racing game if not the best PSP game, period.
I mean, wow, just wow. This game blew me away. I love it. The races don't take all that long, which is good since it's a portable console, and the amount of carnage you can cause per race is fantastic. Not to mention there are just tons of modes based around racing, destruction, or even both.
If you have a PSP, this game is definitely the one to get.