With a group of four (two people down from our normal RPG night group) we played our first game of Arkham Horror. We played it for about 3 hours and got about over the half way point before we called it a night. For a first game I think it went well. There was a lot of rules review, but with the next game, it will go a lot smoother the next time.
Not a short game. The box says 2 to 4 hours and it was more for a first game.
With this being the first time I have played it, I would give it a 7 out of 10. It had a feel of a RPG, like we normaly play.