Eurogamer gave it a 9/10:
http://www.eurogamer.net/article.php?article_id=308326
http://www.eurogamer.net/article.php?article_id=308326
Eurogamer said:Obviously enough, it's worth stressing there's not much here for the single player. But I think the associate oft-stated standard caveat - "as a teamwork game, it's no fun playing with random people" - is far less true than you'd expect. In fact, throwing a group of strangers in a strange situation and then one of them acting strange is the kind of random chaos that Left 4 Dead thrives upon. Things going wrong is glorious. And when things go gloriously wrong, it's the sort of thing you happily blow 500-word intros on. Left 4 Dead is the zombie apocalypse trapped safely inside your computer. Take a holiday in their misery.
In short, Left 4 Dead is another deeply professional, personality-filled and progressive take on the shooter from Valve. In a cultural landscape that has as many zombie touchstones as ours, it takes something special to make them shamble appealingly, and Left 4 Dead, both literally and metaphorically, makes them run. In this new co-op landscape, it'll be interesting to see whether anyone can catch up.