I decided to play this game for the first time today, not knowing how long it was. I'm usually pressed for time but had the day off. I'd say I beat in about 5 hours, which feels good because I'm not sure when I would have been able to play again. I never thought I would like a short game, but this worked out well for me. Next stop: Rage. On a side note though, the game got me amped to defend my 'MERICA, and kind of wished it went on to let me go overseas to plant a bullet in the enemy leader's chest, like in Wolfenstein 3D.
You can beat it on any difficulty between 3-5 hours. I started playing one night just to see where this was headed. 24 hours later, I was already on Act 4 of 7. I work everyday and have 3 kids to take care of. So, my time is limited and this is how far I got just with the little time I have from day to day. Servers for the multi player are no longer up and running. Game is pretty much worthless once you get finished with the campaign.