So it's part of the original trilogy, so that's a good thing. But the infusion of excessive cuteness (Ewoks), and broad humor (Han) drag it down, and the psychodrama of Luke facing both Vader and the Emperor never quite gels. In my current) mind, it's the weakest of the original three (3/5 stars).
http://letterboxd.com/three_star_dave/film/star-wars-episode-vi-return-of-the-jedi/
3 of 5, you're very generous.
+Stan Pedzick I liked it — under a nostalgic and completist penumbra. So 3/5.
Least favorite part: Boba Fett's death by bumbling ineptitude. Completely unbelievable.
Second least favorite part: The Emperor's bumbling ineptitude. Every time Luke was on the verge of turning to the dark side, Palpatine would open his mouth and alert Luke to his peril, ensuring that the plan failed. He's craftier than that.
+Scott Randel The Boba Fett stuff was so awful that I forgave Lucas the particular parts of both the re-FXing and the Prequels that had to do with Boba Fett. Because he deserved better than a ladder gag and a near-Wilhelm.
As to the Emperor — well, he certainly was craftier than that at some point. Since then, he's gotten lazy in execution, jerking around Vader on a leash, mind-dominating the folk he's annoyed by, and generally assuming he's invincible. Think about it — how long as it been since he had to actually seduce someone over to the Dark Side, rather than just ordering them around. Since the Prequels, that's how long.
That whole sequence of scenes is Luke and the Emperor with huge chips on their shoulder as to whose will prevails, with Vader sort of stuck in the middle.