I was at this screening as well, and unfortunately I did not enjoy it as much as OP. Don't get me wrong, it is a technically well made movie, and there is plenty of action, but there seemed to be something missing. I was hoping they would go for the lighter tone of a movie like The Avengers, but it felt a lot more like Superman starring Batman's mood. I guess I have too much affinity for TAS and the Donner films, or maybe I don't relate well to Synder films. However, there are some great moments and it is definitely worth seeing. I just think I got my expectations up too high.
I'd give it a B or a B-. If you want some baromters on my movie taste, Dark Knight - A, Avengers - A, Iron Man 3 - C+, Star Trek 2 - B+
To answer some of the questions:
Cavill's got the look and attitude of Supes, but they don't give him much n the way of dialogue, which was odd. I think he could really blossom in a sequel, kid's got potential.
No hint for a sequel, but I think it's a forgone conclusion.
The first hour felt a lot like Batman Begins, and I enjoyed it a lot.
Michael Shannon was a bright spot as Zod. Really good performance.