So many people go on L4D2 and go straight to online campaigns... I know from experience, so i strongly suggest you practice on single player first so you don't get people mad at you.
Most likely abandoned.
Not finished.
Too many invisable bricks.
Bots do not navagate well at all.
Bots accidently kill themselves.
Barely any amo.
Too foggy.
You get lost way too many times.
Bots do not follow you very well they kinda do their own thing.
More things but, I will not spam you too much.
Conclusion:
A very poorly built campaign, but with a little effort it could be fun.
Pros:
Cons:
Conclusion: