When I was growing up the talk in the schoolyard was always that Vader became Vader after a duel with Obi-Wan.For me,personally,seeing the hellish Mustafar and that final duel was a dream come true.While parts of Eps 1 & 2 certainly disappopinted a friend asked me when I was coming out of the first night of ROTS "What did you think?" and I said "It was everything I wanted it to be" and I still think that about ROTS.