very fun game to play with friends
The Good: most of the achievements are surprisingly easy and satisfying to unlock, shooting your way through wave after wave of zombies, the Co-op is loads of fun, the online play is addicting
The Bad: single player gets repetitive and frustrating (the bots always wait for you to lead the way, and sometimes seem oblivious to you when your knocked down or getting killed)
Other than those minor flaws, i absolutely recommend left 4 dead if you have some friends to play it with, two xbox 360 controllers, or have online play, my final rating for left 4 dead is 8.5/10 (great game)