I found this one intensely compelling because of some of my own mental issues -- not nearly as extreme as those depicted in the movie, but similar enough to identify with.
Adapted (somewhat loosely) from the book of the same name, by Frank Herbert. I never understood why this one got poor reviews. It's not a perfect adaptation of the novel, but there are far worse adaptations out there, and at least this one seems to be earnestly trying; sure it's a little strange, a little jumbled, but so is the novel, that's part of the tale being told. This movie inspired me to love the book, and that alone makes it worthy in my book.
That said, however much I love the movie, I love the book so much more...
The central myth of my childhood, and the classic of my generation. This is also the movie that shows how a strong mythic lifeline in a story can overcome numerous technical flaws. Despite being plagued by poor dialogue and now-legendary uncut bloopers, the mythic vein shines through, and its connections with other powerful myths like the Arthurian cycle only serve to empower it. Less "Sci-Fi" than mythic fantasy, this movie not only puts forth a compelling story of a youth destined to lead a rebellion against an evil Empire, but it also hints strongly at a rich tapestry of history and backstory, tantalizing with glimpses and casual mentionings. Seems to me it was probably a very good thing that Lucas was unable to manifest all the special effects he now says he wanted in these movies, as it allowed the myth and the archetypes to shine. I'd even go so far as to say that Joseph Campbell's part in the making of this movie was probably more influential in its success than Lucas' part was -- or if not, then certainly Campbell and Williams together. This is a movie that still evokes magic, excitement, adventure, and wonder, not only in me but in my children as well.
Technically the best of the original trilogy -- far better constructed, thrillingly dark, no cheap gimmicky stuff yet. The brutal crushing power of the Empire. The introduction of the mysterious and dangerous bounty hunters, from Boba Fett and IG-88 to Bossk and Zuckuss and Dengar. Various strange worlds, from the ice planet Hoth, to swampy Dagobah, to the gas planet Bespin. The first really great lightsaber duel, between Luke and Vader in the carbon freezing chamber. The awesome scene with the space-worm. The shocking revelation. What's not to like? While Star Wars (pardon me, "A New Hope") has a bit more wonder and pure myth, Empire Strikes Back maintains most of that myth and wonder while coming out on top technically -- so I'd say that puts them about equal.
...And this is where we see marketing and merchandising -- the true Dark Side of these films -- beginning to influence things. There were a few toys from the first movie, but it was after the second movie that the flood of toys came, and people in high places began to realize how much MONEY there was to be made from this Star Wars thing.
For a lot of people, especially people a little older than me, Return of the Jedi was where Star Wars started to seriously lose its luster. The main culprit of course being the Ewoks, those cuddly-cute little furry guys just begging for action figures and plush dolls and cartoons to be made of them. But me, I was 8 years old, and I have to admit, Return of the Jedi is still one of my favorites, and still holds a lot of the old Star Wars magic. The brilliant green of Luke's new lightsaber against the washed out deserts of Tatooine. The forest world of Endor, with its towering trees and the speederbike scenes. Luke coming to terms with the truth about his father. And of course, Leia in that slave bikini thing.
In the end, as I've gotten older and learned more about it, I have come to agree with those who mark this movie as the beginning of the end. It should have been massive courageous Wookiees on the forest planet of Kashyyyk where few ever see the ground. Not tiny cute Ewoks on Endor, trundling about and making cute noises while they inexplicably manage to slaughter heavily-armed Imperial Stormtroopers with stick and rocks. Heck, they barely even hid the name change, Wook-ee, Ee-wok. It was supposed to be Wookiees on Kashyyyk, because it was the Wookiees who had been enslaved by the Empire for decades, their strength and technological expertise harnessed to build the Death Stars. It would have been so much cooler if it had been Kashyyyk. But the executives decided Wookiees were too scary and wouldn't sell as many toys to kids. And the dumbing-down began. Next stop: Episode 1, and Jar-Jar Binks. Sigh.
Yet still, this movie holds the old magic for me, and ranks right up there with its predecessors as part of an amazing trilogy. Nevermind the foreshadowing of evil merchandising plots to come, the seeds of darkness, the Wookiee omission. For years after seeing Return of the Jedi, traffic lights at night always reminded me of the brilliant green of Luke's new lightsaber, and the brilliant red of Vader's old one. Sometimes they still do.