Well, I've seen Revenge of the Sith three times now -- the 12:01 a.m. showing on the 19th, a matinee that day, and then again with the kids a week later.
My expectations were so high, and I had so much invested in my pet theories, that I actually didn't like it all that much on the first viewing. I was hoping to see more of Christopher Lee than we did, and really, really wanted a different role for Padme. But the movie closes with some of the most effective scenes of the whole series -- in fact, I was crying by time the final image came onscreen. I loved the next two viewings, and really want to see it again before it leaves the theaters.
Among many excellent accomplishments, the film succeeds in making Return of the Jedi a much better movie that it was before. My oldest daughter wanted to watch ROTJ as soon as she got home from ROTS. Since it was past her bedtime, I had to say no, but we watched Ep. VI the next day, and several lines floored me in the context of the completed prequel trilogy. When Darth Vader tells Luke, "Obi Wan once thought as you do," the meaning became completely different than it had been before.
If you haven't already seen it, go right away. Although I guess that if you haven't already seen it, you're probably not the kind of person likely to be reading this blog. : )
[SPOILER EXPLANATION -- Even if you've seen Ep. III, you might not want to read this without rewatching ROTJ. Before, Vader's line to Luke always struck me as a reference to having defeated his old master -- "Obi Wan once thought the good side more powerful, but I showed him." Now, having seen Anakin crying after he massacred the Separatists, I hear it as, "I recognize that Obi Wan truly wanted to help me when he confronted me on Mustafar." Similarly, the line, "It is too late for me, my son," is more powerful because it's obvious that Anakin has been telling himself this, over and over, ever since the moment he turned on Mace Windu.]