Pretty much the same as its predecessor, which isn't all bad
If you have played Rainbow Six: Vegas, then you have played Rainbow Six: Vegas 2., because this game is almost indistinguishable from its predecessor. This is not necessarily a bad thing, since the first game is easily the best implementation of tactical, cover-based shooting in the past few years. The short length and the sense of familiarity might be a turn-off, but if you enjoyed Rainbow Six: Vegas, you should enjoy #2.
"Vegas 2" continues with the formula from the first game. It starts off in France, but it eventually moves to Las Vegas where, once again, terrorists have taken over. You battle through the streets and through casinos, ordering around your two buddies, taking cover, breaching doors, crashing through windows, and rescuing hostages. The situations are almost exactly the same as the first game, so much that after having played them both, I can't even remember which encounters happened in which game. Is the big oil refinery in the first game, or the second? I forget. There have been some minor graphical upgrades for this game. NPCs, especially, look noticeably better, but the rest of the game looks basically the same. Unlike some other reviews that I have read, I had no graphical hitches or frame rate issues while playing it. The audio isn't much different. It still has great gunshot sounds and lots of good AI barks on top of a minimalist techno soundtrack that you barely notice. Other than a point system that rewards you for scoring headshots, shooting guys from behind, and blowing them up with grenades, the gameplay is basically unchanged too.
The game didn't really need many changes since the first. This series will continue to produce good games as long as it continues to provide the all of the elements that make up great tactical shooting. What are those elements, you might ask? The first is deadly weapons, for both you and your enemies. "Deadly" means that a single headshot can be deadly, and so can a few body shots. A man who is stationary and out in the open is a dead man. Maneuvering during combat requires quick sprints from cover point to cover point. Unlike games like Mass Effect and Gears of War, enemies can't just charge at you because they can take a clip of ammo to the face. Effective use of smoke, explosives, head shots, and flanking is how battles are won. Some situations require you to storm a large, open room, and these parts can be very tough. You really have to stay on your toes to make sure that you don't get outflanked.
Another element of great tactical shooting is functional friendly AI. In this series, your buddies are good at staying alive. They help you take out enemies and they can heal you if you go down. They can follow your simple orders, they don't get stuck on obstacles, and they have no pathfinding problems. Good friendly AI is another feature in this series that makes it better than other games with cover-based shooting.
Yet another important element of this series is great controls. Vegas has a very slick set of controls, although it may take some getting used to at first. The first person view works great for shooting, and then the camera switches to third person when you take cover, so that you can see how well you are hidden. It is the best of both worlds, so-to-speak. By clicking the right mouse button, you pop out quickly from behind cover to take aim, and the game switches back to first person. Controls give you lots of freedom, but they are context-sensitive enough to not be too complex, unlike Gears of War, which has one button for a thousand different situations. You will never wrestle with the controls in this game.
There are some upgrades that would have been nice to see, however. One improvement that this series needs is more variety in how you use your squad. Your squad mates are still stuck together and act essentially as one guy. How about giving us the ability to split the two guys apart and have them storm a room from different directions? The Vegas setting works well for this type of game, but it's not as much of a novelty as it was last time. The fun of shooting up casinos and watching slot machines blow up and fall over just isn't there this time. There are so many interesting places that you could set this type of game. What about The French Quarter of New Orleans or Wall Street? Now that would be cool.
Like the first game, Rainbow Six: Vegas 2 is a bit on the short side (8 hours or so), so it might not be one that justifies a full $50 purchase. Then again, it has been out for a while now, so you probably don't have to pay full price for it. If you haven't tried out this series yet, then you probably should. If the first game left you hungering for more of the same, then you will get what you are looking for in this sequel. If, on the other hand, you are looking for a brand new experience or you just didn't like the first game, then you won't find what you are looking for here.