Not sure at all why this is regarded the best game on the PSP. The tracks are un-inspiring, the sense of speed is totally missing and the handling is terrible – this game's handling is neither realistic (like Gran Tourismo) nor arcade like (Asphalt GT or any number of others). You can sleep round all the tracks – just hold the gas (X) and you'll win everytime. No need to even steer, since hitting the wall has no effect, doesn't even slow you down.
Go with WipeOut Pure instead.