So far I have played 3 out of the 4 campaigns on COOP
And No Mercy + Blood Harvest on VS Mode.
The campaigns I have done with friends and community gamers, only on advanced as we have no idea where we are going. The average start to finish time on those is around 1hr20mins.
Put expert on you are looking at at least 2hours. Considering every time its different I think it will take a while to get bored of it as long as you mix up the people you play with to make it interesting.
The VS mode is damn well great fun, except agree with the previous comment of team balancing. Last night I was playing with a great team to start, we escaped every time on NO MERCY. Yet later on I played Blood Harvest and people we just runnning off on their own and dilly-dallying about like they had all the time in the world or like they were playing COOP.
Still , good times, good game, well worth the money I have paid ALREADY.