The real disappointment of Episode III is that the whole saga hinges on Anakin's moment of temptation. And Lucas totally blows it. It is not believable and conveys no real sense of tragic undoing. As such, it is the 13th note being struck by the clock. It casts everything else about the stories into doubt. If Lucas has so little pathos in him that he can not construct a plausible tale of hubris, temptation and betrayal out of the material he has, the whole thing falls apart and looks worse in retrospect than it did when you could still hope that somehow this story at the heart of everything would vindicate the series. It didn't help that Hayden was a callow, obnoxious kid. But Lucas's writing is the real failure.
Totally agree. As much as I love the Star Wars universe and the way it connects me to my childhood, this was the entire point of the Episodes I-III and Lucas blows it. While I think Hayden Christensen isn't an awful actor and has done some decent work, he's woefully miscast as the future Darth Vader. Any number of current big name young actors would've nailed this. Leo DiCaprio, Jake Gyllenhaal, Tobey McGuire, Jonathan Rhys-Meyers, Christian Bale or Eric Bana would've all done a better job.