I gave it a B-, and it's only that high because of how strong the first part of the movie was. I loved the actors, Cavill was better than what I was expecting, Crowe and Costner were great, pretty much acting wise everyone was great. The story was good, I love the different take and angle of the story. It's an A+, until we get to the action.
I love big dumb action in movies sometimes. Heck, for the last part of the Avengers I had a big stupid grin on my face as our heroes did battle. That is a long action sequence done right. However, it's been downhill from there for me. IM3, ST ID, big "epic" action sequences that left me wishing it would be over after 10 minutes. This is the problem with Man of Steel. I kept waiting for the big epic battle, the Avengers moment if you will. What I saw was one long punch fest, bouncing from one to the next. I was bored, and I was waiting for it to be over. Action for the sake of action doesn't do it for me in movies. If only they could have spent a bit more time on the ending and cut down on the pointless action sequence it might have been a more solid movie in my opinion. They only thing saving this movie from being a C- in my book is the great opening and the successful re-imagining of it.