It also certainly helps that the second half of this film is NOTHING but the stuff we've all been waiting years to see. Lucas has hinted in past interviews at just how it was that Anakin came to be transformed into the formidable Darth Vader that we're all familiar with. Now you'll finally get to see that happen. Phantom and Clones were mere appetizers to this film (and they're actually diminished, I think, by comparison). Sith gives us, at long last, the main course of the prequel trilogy's backstory.
The acting is better in Episode III almost across the board. Gone is Hayden Christensen's occasional awkwardness as Anakin in the last film. Here he only has to brood and glower, but he does it well indeed. Natalie Portman (Padmé) and Ian McDiarmid (Palpatine) finally get to emote rather than just standing around in Kabuki apparel delivering flat dialogue about trade sanctions and executive orders. But the real stand-out of this film is Ewan McGregor, who absolutely nails the role of Obi-Wan Kenobi, perfectly capturing Alec Guinness' subtle nuances of performance in the original films. A real treat to watch here, McGregor too finally gets to express some genuine emotion for a change.
The CG animation, while still imparting a somewhat artificial beauty to the imagery, has never been more intricate and gorgeous to look at. The action, particularly the lightsaber battles, is easily the saga's best (and by a WIDE margin). Jar Jar Binks, though he appears briefly twice, never utters a single word (as 3P0 might say, "Thank the Maker!"). Better still, Revenge of the Sith is absolutely rife with hallmark, connective moments that firmly tie the prequel trilogy to A New Hope, The Empire Strikes Back and Return of the Jedi. And there are two new bits of particularly interesting information that we're given in Sith - things that I have to say came as a bit of a surprise to me. The first is given almost in passing in the middle of the film, and not everyone I spoke with after the screening caught it. The second comes very near the end. Both will force you to reconsider the complete saga in something of a new light.