When playing with friends, Left4Dead gives the best cooperative experience in gaming, hands down. Nothing compares. The game is lacking a bit in terms of content, and more weapons and locations would definitely add to the experience, but nothing can take away from the sheer enjoyment value. Valve's newest might be one of their most masterfully crafted, and the attention to detail is impeccable. It might not win any game-of-the-year awards, but in terms of fun it might beat out anything else this generation has to offer.