I kinda like it but I can see why people are underwhelmed by it. It's a bit like the first teaser for Batman Begins - only at the end did you realise that it was a trailer for a Batman movie and not a drama; only at the end of this one is it clear that it's for Superman. It's clearly aimed at general cinema audiences who may not be aware of the movie's existence, not for we geeks who do.
The end shot of Superman is a little disappointing for those of us who know what the trailer is for. Not quite the same as waiting 10 years to see Clark don the cape and tights in Smallville, then getting a cheapo CGI Superman but I would have liked a clearer look at him.
On the plus, Snyder seems to have moved away from his trademark style and the imagery here is lovely, while the idea of differing narratives is a neat one. I prefer the Costner one, personally. Crowe seems to have adapted a good voice for Jor-El; whether by design or accident, it seems pitched between Brando and Stamp.