Probably more of a team effort with everyone around him, plus his then wife was brilliant at editing the films. For the prequels i suspect it was a case of Emperors new clothes and no one had the guts to tell him to stop!
yeah i re-watched the plinkett reviews over the weekend (they are better than the films) and all the behind the scenes footage just shows a bunch of quiet terrified people agreeing with whatever george said (and him being totally clueless about things).
oh well, the new looks like it might actually be good, fingers crossed.