Ok long winded post ahead!!
I watched Harmy's Star Wars last night and it had been a while since I'd seen it.
First and foremost. Outstanding job done! No matter what you think of the original, the special edition or anything else, Harmy's done a tremendous job and it's as pure an experience as you can ask.
Now the films themselves (original vs special) while I agree with most everyone that Lucas went a bit overboard on the SE and added things that really do a disservice to the movie (the obvious one I'll get back to later), after watching the 1977 version I totally understand why he wanted to tweak the movie and you can see many places where you can almost see his thought of wanting to do more but not being able to.
Now caveat, for Lucas, as for me here, it's very tricky changing something that millions of people have loved, grown up with and have deep nostalgia about.
In a sense, Star Wars is very rough around the edges and edited pretty poorly in some places.
There are several spots where actors' lips are moving but no voice is heard
There are some very obvious loops like the infamous Sand People but also the shooting of the TIE Fighters in the Millennium Falcon and the attack of the cell block where they spend seemingly 5 minutes shooting 2 'cameras'.
There's also a few pacing issues. The most glaring for me were when Luke says "that must have led them.... home!" and he goes to his speeder. It takes him a good long while to get on it and start going and that kind of breaks the urgency of the situation a bit. Likewise during the Battle of Yavin when Luke goes on his final run, right after Han rescues him, cut, BOOM! I seem to recall in the SE he focuses, uses the Force and finally drops the protons. but here it's almost a 1-2 shot and done.
You also have the famous sunset scene where it cut to a different shot and the scene goes from dark blue to deep red.
To me these are the issues most glaring because they are of pacing and immersion and it's 'just' editing so it could have been fixed even back in 1977 (time and budget allowing of course).
Then there are the places in the movie where you can tell Lucas wanted to do more but couldn't because of constraints (whether technology, money or other).
The Stormtrooper on the Bantaa on the dune that's clearly painted, the domesticated Bantaa in Mos Isley that looks like a painting in the first shot and then moves slightly in the next, the destruction of Alderaan which is much less impressive visually than that of the Death Star and surely a few more I'm omitting.
These were the reasons why I see Lucas would want to do his SE, then there are the adds that are useless and actually CHANGE the movie which is the biggest problem and why people have been complaining.
Not to anyone's surprise the biggest for me is the inclusion of Jabba. First showing him in Ep 4 kills the mystique of having him mentioned throughout but onyl revealed in RotJ. Now it's possible Lucas might have wanted to have him in ep 4 back then and couldn't do it but either way it makes no sense because why would Jabba send Greedo to Mos Isley to find Solo if he himself was there already. Plus Jabba is not a hands on guy as far as I can tell so he's much more likely to stay in his palace and dictate than go there himself.
The second and most infamous is 'Han Shot First' which I'd like to point out, is a misnomer because 'Han Shot'. period. Greedo never even pulls the trigger. Han keeps him talking and shoots him, that's it. This change for me is not as awful. Certainly it looses a lot of the coolness but it doesn't change the plot in itself, I find the Jabba inclusion much more problematic.
Now to the plot holes between Star Wars and the prequels. Surprisingly there aren't too many but really one BIG one.
You can explain the fact that Obi-Wan separates Darth Vader and Anakin, you can also explain "you father wanted you to have this" but the biggest hurdle are the droids.
Nothing can explain why Obi-Wan doesn't recognize them, particularly R2-D2. That they became Obi-Wan's property is a stretch to begin with but he spent so much time with them in the prequels that it makes no sense.
Anyway I'm starting to ramble. I'd love to dicuss and sorry if it's OP but it kind of relates to Harmy's version in a sense