I just watched this today and thought it wasn't the worst film I've ever seen, but it wasn't that good. The frequent flashbacks are often annoying and slows the story down, forcing me to grab a beer. It is only during the fight scenes (which there are not many of) that actually interest me. All this feels like is just explanation and little action. I honestly don't like Jon Kent who keeps telling Clark to not use his powers to the point when he stated Clark probably should have let the kids on he bus die. Believe me, I was excited to see him die in a tornado. The film also does some heavy corporate advertising during the first fight with between Superman and Zod's forces.
However, the action is awesome, despite there being brief moments. It's exciting to see Superman fight Zod and his forces. However, without the action, the film is pretty boring.
I would recommend renting this film first before seeing if it worth buying.