Cool game, but not outstanding in any way
Rather than talking about the good aspects of the game, i'll talk about the issues I found. First off, the graphics are unimpressive, textures look too plain and character models are ugly, not to mention that shadows aren't well defined, probably the graphics are the worst aspect of Vegas, and it's a shame because the rest of the game is really cool.
Another issue is that the game is too buggy, a good example are the ropes you use for rappelling, they move in a... weird way... more like they're having seizures or something. Also, when aiming with the 6x scope with the MP5, you see some weird thing flashing on the bottom of the screen. Oh, and weapons dropped by enemies often get stuck in walls and such.
Enemy AI is incredibly stupid in my opinion, either they run out of cover to shoot you or they stick their heads out until you kill them (by the way, enemies die rather too easily in normal mode, but the game is too freaking hard in realistic mode, however, there are enough enemies to make up for the easy kills, you'll even die quite a good amount of times). While friendly AI is a lot more intelligent, they often get in your way: let's suppose you enter a door and see a bunch of enemies who start shooting at you, your first thought is to go back and take cover, but your stupid friends are in the way trying to exit the door, and thus, they get you killed.
I really liked the game, you have to be very tactical and take cover, breaking in a casino through a window and clearing the room is something awesome, but i really expected more from this game, partially because a friend of mine told me there was a lot of customization for your weapons and character. Yeah sure, weapons are only SLIGHTLY customizable, and you can only customize your character in multiplayer... and it's horrible, they got the concept right, but there's some problems I don't feel like mentioning, and your character isn't THAT customizable anyways.
Despite all these problems, is a great game with great gameplay, not to mention it's full of action, and anyone who likes tactical shooters should give this game a try.