Pros:
There is A LOT of zombies. I believe my team and I killd 1,000 in one map. Did I mention there were zombies? It seems scripted.
Cons:
The scripting hurts replayabilty, which is what L4D is all about. On lower end PC's, like mine, there is a massive lag throughout most of the campaign, especially the Witch area.
Conclusion:
While this is an absolutely brilliant campaign, there is little in the way of replayability, but if you play the game to brutally murder any undead/infected that you can, this is the way to go.
Pros:
Cons:
Conclusion: