Just got back from seeing it. It was entertaining - but it's fading from my memory fast. I really don't understand why they bothered making Cumberbatch Khan. He's such an underdeveloped villain in this that it really could have been anyone. Almost a carbon copy of Nero in many ways.
Also - definitely see it in 2D. I went for 3D and it was almost unwatchable on a few occassions.