Well, i just got a PSP3000 w/assassins creed, and we also got LBP-PSP, Gran Turismo, FF Dissidia, and Metal Gear Acid. Anyway, the Gran Turismo for PSP is pretty solid. They threw in a drift mode, which is odd, because usually GT doesn't throw in the funky fake controls where the car will drift almost automatically.
The customization options are limited to swapping tires, and changing ride height really, and moving some ballast around, which is fine. The car list is HUGE for this game, but there are only about 4 dealerships you can pick from on a given "day", on the first day it lets you pick from Honda, Nissan, Toyota, and TVR. It's cool because the game gives you 100,000 credits to start, so you can buy a really decent car on the first choice, and your garage is limitless, but you can only alter 30 cars at a given time with a "quick" customization feature, which is still sorta useless. The game almost gives away credits since there really is no "GT" mode like in past Gt's. You select a race type (drift/race/time attack) and then select a track, then select the car you're using, then hit "go" and you do that once race, then you come back to that screen to choose your next track when you're done. Like I mentioned the credits are given away, the first events are worth about 6,000 and drifts are worth about 3000 so you can quickly buy all the cars you want. Overall, as a game I'd give it a 6/10, but since it's a lot of nice things crammed onto PSP I'll have to say it's a good 9/10 since it will leave me entertained for quite some time. And if you can swap cars with the upcoming gt5, it would be well worth it.