George Lucas had a wonderful vision with Star Wars. Unfortunately he is a middling director and a pretty poor writer to boot. Empire Strikes Back was neither written nor directed by Lucas, and the people who did the honors were much better than him. The result was (by far) the best movie of the lot.
With each new prequil announcement, my biggest disappointment was finding out that Lucas would be directing/writing again. Though afterward, it was even worse to find out that he had some understanding of his writing shortcoming and had someone else pen dialog for the romantic scenes between Anikin and Padme in Clones...dialog that was some of the most painful stuff I have ever listened to.