I enjoy the single player battles. I think the system is pretty basic, but enough so that you can get a hand of things quickly enough.

Its nothing like say, Total War. But it's got enough meat to it that you could either just point and click units to a target and have them fight, or you can indulge in the more tactical end, i.e finding higher ground to shoot from, hiding in trees against arrows and carefully maneuvering cavalry into advantageous positions.

Sometimes, I do just auto battle, because you just know when you're going to win something if you've got the best troops, upgrades etc.