Anywho, if you really want to know if GTA:VCS is a good game for the PSP I suggest you read reviews from IGN, Gamespot, Kotaku, and other gaming websites.
I think it's a pretty good game, I picked it up along with GTA Liberty City Stories, and VCS is a far superior game. The story is really good, it's about Victor Vance, the man with little choice in the game (then again, you could say that he always says 'I have no choice, I must do this' when really he does have a choice). Graphics and animations are updated, and you can actually break peoples necks and the gameplay is really fun (i.e. building an empire).
Overall, it's a fun little game but it's certainly no substitute for a console game so don't complain: "oh, this game's too short", yadda yadda yadda -- it's the PSP. Games are supposed to be short for a reason.
I have the game. It's awsome, the problem is it has a problem with the UMD. For those who are from Romania(like me) Look at the malls for VIVERA. There you can buy the game.