much-loved online co-op mode will add another 10-15 hours of gameplay. If you want to level up your favorite class, expect to take 50-60 hours on that. And then, for the completionist, you'll want 150-180 hours to get all the upgrades for all three classes in online co-op.
Thank goodness you don't have to pay for online access on PSN, as we're sure there are going to be quite a number of people ready to take this MMO-like challenge. Also, we're glad we don't have to level up every class to unlock a Trophy -- that would've been disastrous.
Update: Corrected single player time estimates.