First thing I did, when I had the chance, was put GTA3 in the PS2, and run around in the game while running around in GTA:LCS. Why? To compare the graphics.
Identical.
Arguably, with that crystal-clear little LCD screen on the PSP, GTA:LCS looked /better/!
The PSP needs more killer games (non direct ports), to compete with some of the awesomely innovative titles coming out for the DS. This, while sort of a port, still fits into that category. It's Liberty City, so if you've played GTA3 you will find it VERY familiar. But don't forget, this is Liberty City about 5 or 6 years before the events of GTA3, so some of your familiar haunts will be a little different.
While not as innovative as GTA:SA, this is still a solid game. You can't work out to get bigger, change your hair, get tattoos... none of that. You can't gamble, or to any of the million side-quest mini-games in GTA:SC. Think of this as having all the gameplay features of Vice City (motorbikes, outfits, properties to purchase, etc) in the Liberty City Setting.
The controls are SOLID. I thought navigating cars/bikes with that little analog nub would be an exercise in frustration, but it's very intuitive. Because the PSP lacks some of the buttons on the PS2 controller, some of the control elements have been 'crowded' a bit. Now, to do a drive by, because you don't have an L2 or R2, you have to hold the L button, and press right or left on the d-pad to look out the right or left window of your car.
While it is a little crowded, it's only set up that way for the features that are the least important/used.
If you own a PSP, and enjoy GTA (or are looking for a good 'go anywhere, do anything' game) pick up Liberty City Stories. It's truly amazing!
Graphics: 9/10
Sound: 10/10 (just as many radio stations as in the PS2 versions)
Control: 8/10
Fun: 10/10
Overall: 9.25/10