I saw it yesterday (movie-hopped from Pirates of the Caribbean) and thought it was really, really good. The unconventional character development concerning Superman's return was pretty nice, and Kevin Spacey is an excellent actor.
This was my first experience with Superman, actually, and suffice to say I was a little confused, but I got the hang of things after the main conflict bubbled up and a little bit more insight on the backstory came into play.
And I can't tell you how impressed I was with the CG. The opening credits sequence was stunning, all the effects were outstanding, and they revived Marlon Brando. So awesome.