SpenceEdit did a very nice--and pretty radical--re-cut of Jedi that made me enjoy it for the first time in a decade. It still has some drama and narrative problems, but it was an interesting take on it all. But like the PT I don't believe any amount of editing or SE-ing can fix the film, they can only make it watchable, and there are so many great movies out there, constantly coming out, that it's ultimately a waste of time to devote 2.5 hours just to see something "watchable", knowing beforehand it will never be particularly great.
ROTJ just has too many problems, and they are too firmly integrated to simply be cut around. On their own, one or two of them would be digestible, because the previous two films had flaws too. But together, they are too much, even though I love watching the ensemble together again, I think I would prefer to watch Revenge of the Sith.
-Jabbas palace takes up something like 45 minutes of the film. Too much. I like this sequence, actually, but it goes on for too long.
-Too many puppets and masks throughout the film. I like the uber-exotic style Lucas wanted for the film--but show some restraint. The film goes just a bit too far into Peewees Playhouse territory. When the dance scene comes on, even in 1983, the film stopped dead.
-Recycled plot. This is maybe the most uninteresting thing about the film. More cantina aliens, another Death Star battle. The original script which was set on Coruscant was much more interesting.
-The actors have no real drama. Carrie Fisher sleep-walks through the film and Harrison Ford looks like he is doing a parody of Han Solo--and did someone chop his balls off or what? The character has none of the passion or wit of the other films. But more than that, the character relationships have no tension. Lando and Han are best buds again, for some reason. Luke and Han do nothing but pat each other on the back. Luke somehow is in love with his father now, when the last time we saw him he was babbling to himself in a bloody, teary mess "Ben, why didn't you tell me..." Obi Wan just shrugs off Luke's accusation that he lied to him and was using him for his own personal battles. Luke shows up just in time for Yoda to announce he is about to die, and then does. And somehow, Luke was busy for like 4 months and couldn't be bothered to finish his training--which he is conveniently told he no longer needs anyway. And then Sister Leia is introduced and the whole storyline implodes on itself in a hideous wreckage that the film could never save, no matter how it was tackled--oh well, just enjoy the fireworks. At least the final quarter with Luke and Vader was well done though. Those scenes are as good as anything in ESB, but they are sadly inconsistent with the rest of film.
-Ewoks. As was said, the film revolves around midgets in Disneyland bear costumes who do comedy for thirty minutes and then throw some rocks at stormtroopers, all the while taking only a single casualty that gets his own violin solo to tug at our heart strings.
-Bad dialogue. Despite a couple good quips, the characters don't really have the wit or dimension of even the first film. And sometimes they say too much. One moment in the SpenceEdit that added a lot of dimension to Han was removing the line about the Falcon, "I have a funny feeling like I'm not going to see her again." Instead of saying that we simply see Han looking at the Falcon worried, and we know what he is feeling, we get a private moment with him that no one else sees, and it says a lot about who he is.
-The Emperor. Even though he has become a classic in a sort of cheesy way, if you consider the trajectory of ESB this seems a let down. This is the guy Vader is so scared of? Freaking Gargamel from the Smurfs? All he does is sit there and goad Luke to turn to the darkside, as though the mere suggestion of it is enough to turn him. If I were Luke I'd kill him just to shut him up, which is what I take it Luke was doing when he brought his lightsaber down on his cackling face. The ending moment is good though, but even then if that's how easy it was to kill him I wonder why Vader just didn't push him down the stairs twenty years earlier.
-Bad locations. This one is being a bit nit picky. But Endor is nothing too interesting. It's clearly California, and the few sand-dunes we see on Tatooine are kinda dull too. The Red wood forests offered some interesting photography possibilities but no such luck.
-Bad cinematography. After the beautiful, gorgeous ESB maybe we got spoiled. But films like this that rely on design have to be lit and framed a certain way, and what we got looked like it was intended for a made-for-TV movie. The first Star Wars had that simple style of cinematography too, but it is infinitely more interesting, and with far smaller a budget. Part of the reason I find ROTJ dull is because its so damn boring to look at. If the writing and directing are going to be mediocre, at least give me something visually interesting--this at least the prequels could do.
Finally...there's just something missing. I don't know what. Maybe its just the sum of the total list of complaints above. But there's just a feeling that isn't there. When the Rebel pilots are rushing to their ships in the Yavin hanger, or when the snowspeeders are rushing out and everyone is trying to leave the Hoth base--somehow, when a giant fish walks into a sparkling clean rebel briefing room and a CG hologram of Endor materialises in the centre, it's just not the same. It's not exciting, even if the advanced graphics and exotic design should make it more interesting. But it's not really.
You add up all these things: story, character, dialogue, mis-en-scene, entire sequences, cinematography, casting and locations...that's pretty much the whole movie. You can't re-edit that, you have to re-write and re-film from the ground up. The only thing that's not on that list is music, editing and visual effects, which are all thankfully pretty top notch--the editing is a bit quick, but that's more to do with the script. Some scenes, like on Endor, are not nearly quick enough. But taking a boring scene and cutting it fast doesn't solve anything--you just have a fast-cut boring scene.
If I were to do ROTJ, I wouldn't include a single scene from the actual film, except maybe the conversation between Luke and Vader on the Endor base and the "I am a Jedi" moment. I would throw away the entire film and start over. You probably wouldn't see Tatooine, you wouldn't see Endor, and you wouldn't see a Death Star, and none of the character arcs would be the same either. And with that, you wouldn't have Return of the Jedi, you'd have something totally else, a Sequel to Empire Strikes Back.