This game is simply incredible!
Single Player: Awesome. I'm very impressed with the AI, it's very difficult to beat. In missions, the enemies don't follow set patterns and paths, they'll do something different every time. Friendly AI is very good too, but nothing overly incredible. It gets the the job more than done, what more can you ask for. Great weapon choices, varying objectives, very fun all round experience, and that's what really counts, right?
Multiplayer: Awesome split screen options. My brother and i play split screen tons and love it. Resolution is superb, even with four-way split screen. It doesn't get nearly as fuzzy and whatnot as most games that suppot four player split screen. Xbox live is very stable; it's hard due to the tactical nature of the game, but it's possible to get kills. Very fun to play.
Basically, if you like tactical shooters, this is the best one I've played. It kicks the crap out of rainbow six series, though it is a different kind of game. This game is totally tactics, with wide open levels and smart AI, you're in for a tough, but very fun time. Worth $50, but only is $30, so it's a total steal.