ROTJ was badly written, badly structured, directed in an anodyne way and at times it's painfully cartoonish (Henson style puppets around that time were very much the equivalent to the CGI creatures of today. ESB Yoda = LOTR Gollum, ROTJ Jabba's court = TPM Jar-Jar and most of the Pod Racers including Anakin).
While some of the special effects were amazing achievements those that were were undermined by some really sloppy work mixed in.
If it wasn't for the original cast (some of which are not doing their best) and Ian (who does a lot more work in the film than people give him credit for) it would be just as bad as the PT.
No major characters were killed in ESB but there is a palpable feeling of danger throughout.
Almost every loose end character is dispatched in ROTJ but at no point (even when I was 13) did I feel that our heroes were in serious danger.
The way Yoda is removed from the picture is almost comical in it's current form.
After a few weeks training Luke in the previous film and waiting for him to save Han, Yoda hangs on just long enough to die after a few sentences..."Hi Luke, nice to see you back, I've got a bit of a cough, I'm a bit old, actually I'm going to die right now, oh yeah Vader's your dad...Ben will explain the rest byeee!".
The whole film just feels like a giant post-it note floating in space saying, "Contractual Obligation Finale" in big amber letters.
George Lucas doesn't get Star Wars (he hates the "I know" line).
It's the heavy weight champion of paradoxes.
He gave us all this amazing toy and then charges us cash once in while to watch him smash it in front of us and we still come back for more.