This game is alot of fun if you have 3 friends handy, it boils down to essencialy a 4 player co-op linear shooter, where there is a serious threat of not passing the level (unlike halo). The controls are simple and efficient, and the weapons feel powerfull and familiar.
In terms of content there are only four levels which wile long isn't what you would expect in a full price game, the two counter arguments are that valve has a history of adding content to their games for free, and the new AI directer which you do notice upon replays, and keeps the game at a frenetic pace.
