I think AA was alot more compressed, it didn't really have size missions apart from the Riddler thropies. The amount of other things to do in AC that constantly distract you from the main quest is mind boggling. I spent a 2 hour stint yesterday just hunting down riddler's know associates and doing riddles and/or other side quests (finished the phone booth killer)
So as a result im probably only 80% through the main plot but enjoying every min.
