I just saw it, Id rate it an 8. There are several things that seemed a little wonky to me, like the early departure of Dooku (loved the surprise on his face before he got it) and the somewhat inexplicable appearance of Grievous. Characters just came into this movie with little exposition.
Of course, if you saw the micro series on Cartoon Network youd be up to speed, but that just seems like lazy moviemaking to me /shrug. I sort of wish parts of this movie were spread or begun in EPII, so so much wouldnt have been crammed into this one.
That aside, I think GL dd a good job of getting Anakin's fall across. He wants to do good, but is conflicted (and if you believed Palpatines Darth Plagus story-poor Anakin was almost genetically born to fall). In the end, I really end up viewing Vader as a rather pathetic figure, albeit a murderous, evil one as well.
And Ian Mcrirmind stole this movie. Ewan MacGregor's Obi-Wan was better, becoming more Aluc Guiness-y but Palpatine here was a scene chewer, wonderfully hammy-the perfect tone for a campy space opera.
EDIT: Oh yea - why do I get the idea that GL was leaving continuity open for more Jedi being alive, since Obi wan and Yoda go to the Temple and turn off the fake retreat beacon? Wonder if that will figure into any future SW projects?