Let me summarize Episode 3 by giving it a 9 out of 10.
And now, let me break it down without spoiling any of it (hopefully) for those who haven't seen it:
-- Dialog --
sometimes very clever... sometimes very flat and uninspired. I feel that the dialog was closer in some ways to the original trilogy in terms of humor and melodrama.
-- Special Effects --
Very pretty. Some bits looked a bit fake... but for a film with so many special effects, it was impressive that only a few stood out.
-- Action --
Pretty good. There were some scenes that were tenser than others. There was never any doubt who would die, but it was always interesting to see how a fight would end. I don't think anybody died too easily, although I wish some of the battles were a smidge longer, just for fun.
-- Plot and Integration with Previous Films --
The plot was not overly complicated, and definitely fills in many gaps that I was aware of. There is a lot that had to be covered in this film, so it is cut very quickly, and what must be weeks pass by in moments. Even some topics that I thought would not be addressed actually were. Very nice touches to tie this movie in with the original trilogy. Characters behave believably, making the plotting of the Sith seem even more devious... some people may complain that some characters change too quickly, but as I mentioned, the movie covers a lot of ground so weeks pass by in the blink of an eye.
What more can I say about this film? Was it perfect? No. But it is the second best Star Wars film to date, behind The Empire Strikes Back. There are many cool and amusing moments that will make me want to watch the film again. And in many ways it justifies the first two films (which I'd give a 6 and 8 out of ten, respectively).
So there you go. Watch and enjoy. :)