ANH provides a solid introduction to the universe and a tightly paced self contained adventure within it.
It's visually arresting and you gain enough from the performances and screenplay to appreciate and want to be with those characters as they go through that adventure.
It has a few continuity errors which will probably be missed on repeated viewings a couple of effects which don't match the quality of the rest of the piece which are bound to be forgiven on the first viewing.
ROTJ is (in my view) a step backwards from that.
It's fun but if you park Mark's contribution for a moment (as it's the real jewel in that rough) it has as much general character involvement as Saga Of A Star World (if not less).
The legacy of the first two films and the fans deserved better after six years of waiting.
TPM was more of a disappointment but as the whole PT is screwed up I can partition those films into a different part of my brain.
I don't have that option with ROTJ.