I played the demo round a mates house the other day, was so impressed I went straight out and bought the game. It's very well done, and works really well. Just getting started in the single player campaign, done the first few levels, pretty tough going!
My online tag is norfolknclue. use the /addfriend command in the chat window and it will pop up a request. Been playing it since it was released - pretty much the only game I play online at the moment (apart from a quick blast on Defcon).