[quote name='heavyd853']So I just read the IGN review for Left 4 Dead, and it says there's only 4 scenarios....and that you can finish each in about half an hour.[/quote]
I declare this bullshit, but I think IGN usually is. I played the full first scenario (No Mercy) last night on advanced, and with only restarting from a full party wipe once (at the very last stand) it took us 90 minutes. The only way I could even imagine it taking 30 minutes is just pure running from start to finish.
Personally, I think L4D is one of the best games I've played in a long time. I had so much fun, and I can't wait til I'm out of class this afternoon, so I can go play more. I know I'll be playing through all the scenarios multiple times, including attempting to beat each on Expert, which I expect to take a long time.