"Return of the Jedi" is often remembered for what it did wrong rather than what it did right, and that is a shame, because the last chronological installment in the Star Wars saga is a shining example of epic storytelling. It manages to wrap up all story lines of the previous movies in one grand finale, and does so very convincingly.
Yes, there are Ewoks - cute and cuddly bears that arguably served to broaden the Star Wars demographic - and in the middle the movie tends to slow down a bit. But the final hour is arguably the best piece of the entire saga, where Luke finally comes face to face with Darth Vader, the most recognizable villain in movie history.
Return of the Jedi did so many things right that people tend to overlook: it presented an incredible conclusion to the Darth Vader storyline (which went from slightly implausible in the "Empire Strikes Back" to very convincing here), an exciting opening at Jabba's Palace, a masterful performance of Ian McDiarmid as the Emperor, Luke finally coming into his own, the resolution of Solo and Leia's romance, and the extremely powerful final moments on the Endor moon.
Yes, there are slight annoyances. But they are the annoyances of a generation of moviegoers who've had time to nitpick every single scene. It's still a magical and moving piece of cinema that also serves as a great final chapter. It's not a 'good' movie - it's fantastic!