Vegas on the PSP is a watered down edition of the console game with stiff controls and muffled sounds.
On the PSP, your mission originally is to rescue two members of your team who have been captured by terrorists. ALong the way you end up stumbling upon an impending nuclear disaster and your priorities change.
In gameplay, you alternate between two characters, Brian and Shawn, one is armed with an automatic rifle, the other with a sniper rifle. For both characters, the control scheme is the same. the D-Pad are action buttons, the control stick controls movement, the four shape buttons control aim, L is fire, and R is an auto aim. If it wasn't for the auto aim, I would've loathed every moment spent on this game. Trying to use the shape buttons for looking isn't practical and it's far too stiff when you need to shoot a guy down who is getting you from behind.
Visually, the game is rather bland, none of the environments are especially large, or stand out as something different. There is some cause for credit here however, in that character models have plenty of detail to them.
Sound is less than pleasing. Nothing ever really sounds like a big boom, or a rat-a-tat of an automatic. It all sounds half-hearted and muffled. Throughout the game, I didn't notice any music going on in the background. Unfortunately, I can find nothing really redeeming in the sound department about this game.
Replayability is also very low with this game. The campaign itself is very short, I was able to beat the campaign start to finish on nothing more than lunch breaks in a week. For me, that means about 4.5 hours of game time. Also, the only incentive to go back in is to unlock stages for multiplayer.
Speaking of which, I found multiplayer was subject to the same stiff issues as I had found in single player and after a few deaths at the hands of stiff controls, I had little ambition to go into a match again.
Despite my complaints, I'd recommend this game to someone who wants something to do on their breaks, wether it be a few 15 minutes, or hour long lunches.