Very different, very intense, very.... good.
Vegas tried to bring this realism back, but along with that, it tried to make itself enjoyable for console gamers, with limited abilities(lack of a whole set of keys, aiming is problematic, and the list goes on).
Did Ubisoft suceed with that? Yes. The game is one of the best First Person Shooters of the year.
First of, the gameplay is very intense, and you won't find a boring moment. The game has an interesting story too - nothing big - but it's there, and it's interesting enough to keep up your interest.
In the game, you fight against terrorists. Mostly in Las Vegas. Mostly in casinos and... mostly with a team.
The realism, as I mentioned is there. You won't be running around the battlefield. Run and gun 'tactic' is something you should forget. Even on normal difficulty 3-4 bullets can take you down. Also,a new cover system is introduced. You can basically use anything as a cover. A car, wall, table, whatever. When you jump into cover, the camera switches into 3rd person view, so you can have a nice view on the terrorists, but you cannot be shoot, because you're hiding. Pretty clever. And it works well too, the 3rd person view isn't annoying. At all.
Graphically, the game is a mixed bag. It uses Unreal 3 engine ,which is brilliant. But the developers didn't bother polishing it very much - the game looks like Lockdown at some places - but then, at other places, it looks so 'next-gen'. Unfortunately, that's not enough to make up for the horrendous system demand: the game runs at 18 - 25 fps on a 7800GT paired up with an A64 3200. What's worth mentioning is the physics. Awesome. Most of the stuff is destroyable, and, the guns act just like they SHOULD act. Great recoil.
The music is top-notch, it definitely boosts the adrelaine at some places. However, the sounds, especially the voices are a little low quality here and there, but that's ok.
The only negative thing I can think of besides system requirements is the save system. Simply put: it sucks. There is checkpoint-system, which normally works well, but in Vegas... it just doesn't. The saves are not before, but more likely AFTER big firefights. I tell you: it's incredibly frustrating to play 30 minutes, survive a huge firefight, then you get one bullet in your head - you die, and you can re-start the whole mission. 30 minutes again. Besides that, the game is excellent, and a must have if you like FPS games, and if your computer is beefy enough![Note, the game does not run on videocards supporting SM2 only: Radeon 9xxx series, Xxx series, Nvidia Ti series, Nvidia FX series].