The previous two films came in at 62% and 65% respectively for general reviews but only 40% positive from the "Cream of the Crop" reviewers. I tend to agree with the 40% number on Episodes I & II. I won't even begin to talk about why "Phantom Menace" was so terrible... well, ok, I will: Terrible miscasting of the young Anakin, WAY too involved and convoluted as far as the trade issues, "midichlorians", immaculate conception, and of course, Jar-Jar.
"Clones" was far better except for Hayden's performance (which I don't entirely blame him for) and the whole Anakin/Padme romance.
The buzz on Episode III has been building and people have been hoping that it would make up for the previous two films. The first glimmer of hope came when rumours of a PG-13 rating surfaced (since confirmed) and then when images started to appear indicating the dark nature of this chapter. Now the reviews are coming in from both hardcore Star Wars fans as well as "regular people" and it's actually looking like this may turn out to be on a level with The Empire Strikes Back, which by any measure is considered the best film of the series to date.
Of course I expect weakness in this film: I'm hearing that the scenes with Padme are pretty weak as is the love relationship (again). That's a shame is it seems to be such a crucial plot point for the Darth/Anakin character. On the other hand I'm hearing that the first and last thirds of the film more than make up for that middle third weakness.
Put me down as officially cautiously optimistic.