I really enjoyed playing this game; the squad mechanics are very good, the tutorial is done well, there is a good variety of missions and the tension really builds well. I don't normally play shooters but the price persuaded me. The graphics are also very good. Kill-cam (showing you how you died) in multiplayer is a good innovation. My favourite bit was the introduction, very different and sets the tone perfectly. In short, singleplayer is awesome.
I guess there is nothing major. The story is very vague, something about a generic middle-eastern country that we never learn the name of and a few russians chucked in, with the usual rubbish about a bomb. Stereotyped Brits who still use american words like "dumpster"! The game is short, but then I am used to open-ended role playing games. My only major niggle is multiplayer; other players aren't friendly and it is near-impossible to compete with people who have spent two years honing their mouse-clicking to millimetre accuracy; prepare to get shot a lot!