Really, really good, which is a relief, because I haven't seen a summer blockbuster that I've enjoyed in a long, long time. It has an operatic grandeur, aided again by the Wagnerian themes of the score by Hans Zimmer and James Newton Howard. Much better than Batman Begins, which I wasn't as crazy about in execution as everyone else was (though the concept of a darker, more realistic telling of the story was great).
See it in IMAX. Seeing it at a regular theater you will get a pan-and-scan version of about 30 minutes of the movie. It won't be bad, but if every there was a movie you had to see in its native format, on the bigger-than-big screen, this is it. You won't be able to replicate this in any home theater. The cuts between the 35mm shots and the 70mm IMAX shots are near seamless, and you barely notice them (they're easier to spot when going from IMAX to 35mm than vice versa.