First three work just fine.....Not any plot holes I can tell other then Luke kissing Leia...which is just four kinds of wrong.
I'd be willing to write off St*r WarzzZZ as a fluke, if it where not for American Graffitii and THX-1138. Both where good movies with good scripts. St*r WarzzZZ was really the biggest of 3 hits movies that he had written and directed in a row. So he had something.
And Lucas himself will admit that a lot of SW was stolen. He took what he liked, threw it into a blender and then presented it in a way no one had before. That was part of the appeal of SW. It was so radically different, yet so familar all at the same time.
But it was after SW that GL did what he should have done for the rest of his life....and that was come up with Ideas and let other people handle the foot work. After SW he was sucessful enough to do that, and he should have kept doing it. Cause when you really look at it, he is a amazing creator and storyteller, but a medicore director and one of the worst Screen-Writers ever. There almost has to be a buffer between Lucas and the public made up of Producers, Screen-Writers, and directors to turn his idea into something marketable. When Lucas is the producer, writer, and director we get the Prequels. Which at their core, the prequels where good stories that went so wrong in the details. If he had people like Kurtz(Producer SW, ESB,The Dark Cystal )and Lawrence Kasdan( Writer ESB,ROTJ, Raiders of the Lost Ark, The Big Chill) working on them they would have turned out far better. Instead he had Yes men all around him like Rick McCallum. That's how you get talking jackass Frogs and offensive Sterotypes mixed in with some of the flatest dialouge ever.