I can't wait for this game, it looks to be amazing. People will believe that this game will be exactly the same as the first but it won't. Why? Because of all the new features in L4D2. Such as 10 melee weapons including a chainsaw, katana and a frying pan. 3 new special infected, the jockey, the spitter and the charger. Improved models of the old SI including a female version of the boomer. Uncommon common infected like the clown and hazmat zombies. New weapons like the Desert eagle and grenade launcher New pick-ups such as the bile canister, which (hasn't been confirmed) sounds like you are able to throw them at enemies like a tank and all the common infected go after the tank instead of you.
Plus a new game mode called scavenge which gives you all the more reason why you should buy this