My experience:
Tried 2 players to start. Had loads of people telling me it would be 5+ hours of unboxing and setup before we could even play. It took us less than 2 hours to get into our first game, it wasn't that bad at all. We got killed badly though, lost the first scenario. Went to bed and got back at it in the morning. 2 more failed attempts, DAMNIT!
Figured out on a break that we were playing on normal instead of easy difficulty, sons of bitches! Tried one more, we got a lot further into the scenario, but still died on the last couple monsters. Gave up at that point as we'd played about 12 of the preceding 24 hours including a few hours of sleep...
After stopping, we realized we were also doing the monster AI completely wrong, no goddamn wonder they were wrecking us so hard! Next game night we figure to have a much easier time and hopefully get through a couple scenarios..
Biggest thing for me is it's not nearly as hard to re-setup as I thought. No problem getting another game going with the same group in 15 minutes or so.