For me the fatal flaw is the high reliance on greenscreen for everything from special effects to virtual sets.

None of the CGI (or miniature comped) sets seemed tangible, there was little interaction between the actors and their environment besides shooting and slicing and sitting in cockpits. The rest of the movies seemed to be sitting or standing around.

The technique is probably perfected in Avatar, but even that flick left me cold and no yearning to go and see it again.

I remember reading the novelisation of TPM before seeing it at the cinema and thinking the story played out pretty well. So it's a flawed execution. Poor direction. Did Lucas even leave the video village?