Only played like 30 mins of this game so far (played like 4 hrs of the demo too) and I love it!!
Really built on the first one, and added lots of nice touches. I love the dynamic "panic" events, melee weapons, and new guns! So far, gota love the Magnum & the new Sniper!! The weapon upgrades are cool too!
So far, this game has impressed me much more than CoD: MW2. Although MW2 is a very fun game to play, it just dosent live up to its hype. But then thats off topic.
To put a number to it, Id probably give L4D2 a 9.5/10! (nothings perfect

) Also love the fact that if you pre-ordered the game, you get it early!! IT unlocked yesterday for me, but still says get it on the 20th on Steam, and its not in-store yet! EPIC! Again, unlike the MW2 release.... not only is it no cheaper to pre-order (L4D2 was, £26, instead of £35) but you get it 2 days LATER than the people who buy it in store!! (They then get to put it on steam anyways!! what the heck??)