For anyone not picking this up I'll tick off a few ideas that I think they foolishly abandoned or changed starting with probably the major one

Even Brad Bird in his forward, after making sure to be as complimentary and positive as possible (he is after all a peer and counts Lucas now as a personal friend and mentor) admits that as excited as he was as a teen for the film's release, he walked out of the theater in May '83 with many of the same 'beefs' I'd had.
If you go back a few pages, this is almost word for word what I'd written years back.

Interesting then that in one GL's very first pass at a story treatment he has in the first act

• Vader first face to face with the Emperor has them talking then arguing
• the Emperor and Moff Jerjerrod then are shown plotting against Vader
• Leia does not abandon her duties to Alliance to run off and help save her boyfriend. In the first act she is already involved in a separate mission (on the moon similar to mission in the final film).
• In the first act Luke is also shown trying to resolve things with Yoda and Ben before going to Tattoine.
• The rescue of Han takes place in the second act.

A subsequent variation has Lucas toying with the idea of having the Emperor capture Luke (on or near Tatooine) with the purpose of keeping him away from Vader.

While all this unfortunately still operates within a basic lazy plot of "there's a new Death Star we have to destroy", at least we now know the characters were being considered with an eye toward stronger emotional and expressed continuity.
Key here for me is a first scene between Vader and the Emperor that would have been VASTLY SUPERIOR to what ended up on film- not only because it flows organically from the stated convictions and mindsets of these two characters from the last film, but because it also points the way to more interesting and mature conflicts that would have had to play out and get resolved over the course of the film.

This would have been the first scene from the film, as Vader is summoned to appear before the Emperor

At this point Vader tries to establish a mental contact with Luke, warning him of the Emperors plan and reemphasizing their need to join forces and defeat him.
At this point Yoda enters his dream state and warns Luke not to be confused by Vader. Luke questions both Yoda and Ben on why they didn't tell him sooner...

There are several things here I just love.

1) continuity from ESB.

• Vader was given an assignment and failed and there is consequence from the Emperor for it.
• Vaders petitioning to luke to join him was a concrete idea that is followed up on ...and the all powerful Emperor is shown to be suspicious immediately.
  This is a FAR more powerful and commanding conception of the character rather than the passive wizend crone that changes his all important goals for no real reason.
  (" eh, forget what I said in the last film. There's no urgency in getting luke. Eventually he will come to us.")
• Luke is early on shown as wracked with doubt and confusion over what he has learned in the last film. He is NOT a swaggering bad ass. He has clearly been impacted by the last films events and that is carried right over here.

2) New and interesting conflict is established right off the bat

• Vader is now in clear conflict with the Emperor
• Jerjerrod is also positioned as a point of conflict for Vader to navigate around
• the very first scene with Lukes is where we see the conflict raging in his psyche. This isn't put on pause for the first act so we can have a feel good set piece and then we hit play again. We are going to see the character have to function throughout the film with this underpinning all his actions and motivations.

3) the way the Emperor is portrayed. His mean spirited, condescending tone; the way he uses "we" which implies another realm of evil that he is apart of that Vader isn't privy to; the way he is shown as powerful active and engaged- not passive and reactionary.

I'm still working my way through the book (the story development is given a generous amount of the books page count...probably around 60 pages at least) but these were things that tickled me to see almost immediately.
Even within the framework of "Hey it's another Death Star" and "Deadbeat, mass killer dad is my best bud after all", there were some honestly sound attempts to knit this stuff together into a much more nuanced and sophisticated whole.