First reviews from people coming in from media screenings are hitting now.
I won't post any that I've seen, as they're all INSANELY spoiler heavy, but the general impression is that its definitely the best of the Prequels, but maybe not as good as ESB. Very dark, seamless CGI(more so than AotC), and Yoda and Palpy are the show stealers. From the sound of things, this really is the Star Wars we've been waiting for...and this is from fans that have been waiting for it.
Jedi Purge scenes are, apparently, the best in the movie, if not the best scene from all six.