Something that is apparent to me is the cheap shortcuts that Lucas takes when messing about with the Trilogy. These films mean so much to so many people but these quick fixes would seem to reveal a lack of respect for the fans and the films.
1. Luke's scream
We all know the bizarreness of Luke's added (and since removed again) scream as he falls in ESB. What is stranger, however, is why Lucas saw fit to simply use the Emperor's scream from ROTJ and not record anything new. Very obvious to fans.
2. Vader's arrival
For reasons known only to Lucas himself, the 'Star Destroyer' arrival scene added to ESB is footage from the Death Star arrival in ROTJ. Same docking bay, shuttle and background. Even Death Star Commander JerJerrod is there to greet him - clearly mouthing the words he says in the subsequent movie. Of course, it is not "an unexpected pleasure" as Vader's newly dubbed line on Cloud City is much more expository than the original.
3. Boba's new voice
Whatever the merits of changing the voice, few could argue that the reading is very poorly done. I doubt that Temuera Morrison even watched the scenes he was dubbing for as he rushes through his lines.
4. Added Naboo Scene.
Lucas thought that this planet should be included in his continuing montage of celebrations. However, simple re-using a scene from TPM and flipping it would seem to be a lazy way to do it. It would appear that Naboo has remained 100% unchanged through Imperial Rule!
5. Hayden Ghost
Having decided that there is no good in Vader after all and that Anakin died in episode 3, Lucas decides to add 'evil Anakin' into ROTJ. There is some debate as to whether this was filmed especially for ROTJ or whether it is taken of Hayden in the ROTS canteen. Certainly the acting, expressions and total lack of eye line would support the latter.
What is certain is that Lucas felt no need to put Anakin in a relevant costume, instead opting to cut and paste Hayden's head onto Shaw's traditional robes. Robes that Anakin never wore.
If Lucas is so passionate about his vision, why the laziness in implementing it?
The most important people for any filmmaker, the reason that I make films, is for you! The audience rules! ~ George Lucas