A masterpiece of cinema. The film transcends the franchise, seamlessly combining elements of myth, science fiction, fantasy, war film, romance, bildungsroman, epic and tragedy in a way that its sequels have been unable to replicate. It is a move without a moment of fluff. Cut anything and the film would suffer. Story, character, effects, cinematography, music, screenplay, acting, editing and action are all superb. One of the most artistically poignant films ever made. And because its style cannot be replicated, it will continue to appreciate with age.
This was a time when George Lucas still had integrity, as evidenced in this 1980 Rolling Stone interview (he has since contradicted much of what he espouses in both word and deed): https://www.rollingstone.com/movies/news/the-empire-strikes-back-and-so-does-george-lucas-19800612
Here's a blog article shows Empire's cinematic chiasmus, or narrative symmetry: https://dejareviewer.com/2014/05/20/cinematic-chiasmus-the-empire-strikes-back-is-a-perfectly-symmetrical-film/
My favorite version is the Team Negative1 Renegade Grindhouse Edition, an unrestored 35mm scan complete with damage and dust. The Despecialized version is okay too. All official releases are desecrations.
People may say that Star Wars is dead, but The Empire Strikes Back is deathless.