It didn't suck.
Any time romantic dialogue was spoken, it was like having a root canal. Fortunately, they kept this to a bare minimum this time around, which is good. The rest of the dialogue wasn't any worse than it ever is. (It's the romance where Lucas seriously can't write. Oy, the pain.)
Ewan McGregor did all the heavy lifting acting-wise. This, again, will surprise no one. Also, he's hot. Again, this will surprise no one. His riding lizard was also neat.
A few eager reviewers have claimed this made up for Episodes I & II. They are wrong. The dialogue in Episode II will go down in history among humanity's greatest atrocities, and we won't even get started on Episode I. However, taken alone, III is not a bad movie. James will even allow that it was on par with Return of the Jedi, although of course it was no Empire. There were even moments that recalled the original Star Wars swashbuckling good-naturedness, and General Greivous can lead my rebellion any day. The action was good, although we would expect no less.
The wookies were sort of gratutious. It was like "Look! Wookies! You LIKE wookies, right?!" I do like wookies, but this felt more like product placement for some kind of wookie soft drink than actual productive use of wookiekind.
Anakin was still annoying, whiny, and deserved a good slapping, but it occurs to me that his real problem is the shadow of Darth Vader. He's really no more annoying, whiny, and slappable than Luke, and considerably less inept, if apparently utterly humorless. (Okay, the jedi-teen-stalker dialogue is unforgiveable, but we'll just pretend Episode II, like Highlander II, Never Happened.) Were these movies about somebody else, I could have unbent enough to actually experience a little pathos and say "Okay, yeah, I feel for you, you stupid kid. Also, you're undeniably good looking as a Sith as long as the robe hides most of your face." However, they are about Darth Vader. We all LOVE Darth Vader. We respect Darth Vader. Darth Vader is just an impossible standard to live up to.* So of course it failed on that front. Christian whatsisname was simply not cool enough to become the Darth Vader we know and love, and I still find it vaguely repellant that the greatest Sith around goes over the Dark Side more or less over a chick, because...c'mon. Vader. *sigh*
But still, it didn't suck. And nary a loose end in sight. So it was worth seeing, for itself, not just out of a fatalistic sense of completion.
And c'mon. Four-armed lightsaber droid action. You gotta love that.
*Possibly if James Earl Jones had done the voice acting for the entire movie--except perhaps Episode I, where that might've been a little odd--I would feel differently. I will forgive that voice a lot. I could listen to him read the phone book. Reading Lucas's romantic dialogue, though...well, maybe it's for the best.