Let me first start off by saying that I haven't understood the rage behind the Rainbow Six series ever since it first debuted. Not only did the game always run on a crappy engine... The AI was ridiculous and in all of the titles you were unable to pick up your enemies weapon. You fought stupid terrorists that wouldn't even notice you shooting a bullet past their head, but if you accidentally moved past the wrong area they'd just kill the hostages. You'd be stuck with dumb AI teammates that never listened to what you said, and the action in the games would just crawl because you were more busy managing your team and hoping their moronic asses didn't get capped before you could clear a room.
This of course improved as the series evolved... But not by much. The games always seemed to be released like one big cash in and never bothered to truely reach the potential that a squad based tactical shooter could.
Surprisingly, Vegas kicks larges amounts of ass. It uses Epic's Unreal engine so it looks just about as good as Gears of War ( THANK YOU CONSOLES FOR CATCHING ON TO THINGS LIKE GOOD GAME ENGINES ) and plays twice as good ( I could be exaggerating but I like this game a lot ) . The stop and pop of Gears is available in this game, but you're not stuck to walls and all of that like you are in Gears. You simple just hold a trigger to worm around the walls or pieces of cover around you. The game has all of the right moves to keep even non FPS fans engrossed in the action.
It's the way the game should have been all along. The game doesn't feel clunky like it used to on whatever shite engine they were using for the last generation of games, the controls are excellent, team and enemy AI is actually reasonably intelligent ( Especially on Realistic ) and everything just feels RIGHT with this title. The AI improvement is the best part I think, because anyone who has played an older Tom Clancy title like Ghost Recon know how terrible the enemy AI can be at times.
What's really weird is that you now only control 2 additional teammates instead of having six altogether... I don't mind it myself since it makes controlling your team fairly simple ( The control scheme is really easy ) but it does take away from some of the cool tactical things you could do with a six man team.
I'm only about 3 levels in, have played 4 or so random levels on co-op with a friend, and have spent a few rounds online. I can't really comment too much about the online play, but co-op is pretty badass and really makes the game quite enjoyable.
Some complaints from hardcore Rainbow Six fans might be that the game is a bit more action based and not as tactical. You don't really need a huge master plan to take out areas of terrorists and your teammates can be revived at any time Ala Gears of War as opposed to having them die off and leaving you on your own. I don't really care myself since I'm more of guy who likes to shoot first and ask questions later but hardcore fans of the series may be kinda bummed
I dunno... You just need to play it for yourself. It is most excellent. If you have played, you like?