You cannot seriously compare the PSP version with the PS3 version. The controls are different, but you should know that if you own a PSP in the first place! It takes about 30 mins to get used to the controls but once you have its easy to play.
The levels are challenging and its definitely not a 'run and gun' action game but more suited to people who use stealth, a bit like the SOCOM games in that respect.
The graphics for a PSP game are among the best i have seen and the online multiplayer was rich and in depth for a handheld game.
Can you compare the games on the Wii to a Nintendo DS? No
Can you compare the games on the PS3 to the PSP? No, so stop trying!
Its a great way to take Vegas on the road on long journeys, the bus, train etc.
This game has both atmosphere and gameplay and for that reason I am giving it 5 stars.