I managed to get through the same amount with 4 players in about 4 1/2 hours so sounds about right. We went win-win-loss, and two of the three other players are demanding another shot tomorrow to rectify it. I've loved it so far, but I'm hoping the brevity of the first two chapters don't carry over. C3 gave me hope of that ^_^
The first two chapters are intentionally shorter. There is some introductory learning of the game and choices on character development that we thought were important enough to devote games to, but we didn't want experienced players to have to play a simplified version of the game for too long.
Once you get to Chapter 3, you are playing a full game of Aeon's End with all of the rules. Then, we build from there for more awesomeness.