Two words can sum up this game... Absolutly Terrible!
The graphics are terrible. The PSP isnt a weak console, graphics wise, just look at GTA and Tekken they are PS2 quality. This game however has sharp textures and horrible looking character models, the frame rate isnt much to talk about either it can easily slow down or completly hitch up if alot is going on around you.
The sound is pretty much the only decent part of the game, like the console versions the gun sounds and general SFX are pretty impressive.
The gameplay is terrible. The main story is over way too quickly and the storyline isnt as nearly as good as the console versions. Each level has a pretty basic terrorist hunt mode. The online isnt very good either, there is rarely anyone to play against online and if you manage to find someone then the LAG is incredibly bad. I cant say anything about the Ad-Hoc multiplayer because no one I know has even bothered buying the game.
If you are thinking about buying this game, DONT. Seriously, even if your a fan of the series or you just fancy a change its not worth any amount of money. I am fed up of seeing watered down ports of next generation games, the PSP can do alot better.