FINALLY.Annoyingly, I'm going home to a laptop without the capability to run Empire in a week, so I won't be able to play it for a month or so. But yes. Coop campaign sounds quite interesting, especially since you can double team the AI in battles. Then stab the other player in the back. The potential to have the other player take control of the opposing AI should certainly spice up the battles tactics-wise, too.
As I said, can't really play at the moment (won't have the HD space until I've finished with Mass Effect anyway) but if you have a go, let me know what you think!