I was disappointed that they didn't have Superman defend himself properly against Luthor's thugs on Kryptonite Island. It would have been something to see that Superman can still hold his ground even without superpowers. I dislike the portrayal that every time he loses his powers he turns into a pussy wimp.
Well the idea seemed to be that the kryptonite sapped pretty much ALL his energy. Even standing up was a huge struggle.
Personally I loved the powerful and heartbreaking way that scene played out. My only complaint is that we didn't get to see Supes get back at Luthor and his thugs later on. The villains were either conveniently crushed by falling debris or ran out of gas and got stuck on an island.
Not exactly the most satisfying way to end things.