As long as its nothing like an mmo im happy. Id just love something like a split screen option. There was a moment in morrowind where I was levitating my way to the urshilaku camp and shooting fire balls from hundreds of feet in the air into cliff racers and thats when I thought "how sick would it be to have a friend here with me flying through the air having a magic fight?". I can see why people would disagree though.
I wouldn't mind a coop. It'd be nice if they could take over your allies making for a smarter, not stronger companion. Coop would only become available after you've progressed through a faction far enough to where you COULD get an ally.
What I would really like to see is something like Fable 2/3 did where you could see orbs representing other people playing their own separate single player experience; where interactions are limited to seeing what kind of armor they possess, stats, and the ability to communicate, as long as you're in the same area as them. --- Gamerscore: 17265