Really is a fantastic game if anyone's on the fence about picking it up. I grabbed it a few weeks ago and have been playing with some old friends who I started computer gaming with in the early 90's. Got burned out on the genre a long time ago (with the exception of Bioshock in recent years), but I've been having a blast with this one.
If you're playing with good people (or at least people you know), it's ridiculous amounts of fun. The animation and sound effects are great, and you definitely have those moments where everyone's just about dead and you're all paranoid about what's around the next corner. Then you hear a boomer gurgling or a tank rumbling and get that sinking "Aw, crap" feeling. Just a great game.