Saw this a few nights ago (wanted to go earlier but between kids, family vacation, work and, well, life, I no longer get to the cinema nearly as often as I used to when I was single).
Gave it an A-. I'm glad I went in spoiler-free (I usually do that for movies--didn't do it for the latest Trek and while I still enjoyed it immensely, I regret dropping my usual spoiler-free policy). Made the death of Zod moment more powerful.
Overall, I was entertained (first order of business for a movie). I had no issues with the "updates" to the mythology. Casting was first rate. My only quibbles really have to do with the lengthy action scenes. There is nothing specific I consider objectionable about any scene or shot in particular, but some judicious editing could have shortened them a bit without sacrificing the overall effect of demonstrating exactly how powerful such beings would be (and the consequences of that power). This could have freed up 3-5 mins. in the running time for a bit more development of Martha (of all the important characters, she's the one that most felt, to me, like a few more moments of screen time would have been beneficial--plus I'm a big fan of Diane Lane). Not in one chunk, and not solely Martha--a few quick moments with Martha, Jonathan and Clark together (beyond the truck/tornado scene) would have been nice. It seemed like it was Clark/Martha and Clark/Jonathan but rarely all three together. But these are minor quibbles.
I was a bit sorry to see Hamilton die--thought he'd make a good recurring minor character.
Nostalgia, at present, keeps the two Reeve films at the top of my favourites list for Superman film/TV, but that could change with a few more viewings of MoS. I'm certainly looking forward to further outings from this production.