Buried in The Dissolve's sprawling "The 50 Greatest Summer Blockbusters", Noel Murray provides the clearest outline of why The Empire Strikes Back is the greatest Star Wars movie, and what J.J. Abrams do from the first scene of his upcoming sequal:
Director Irvin Kershner and screenwriters Leigh Brackett and Lawrence Kasdan forced George Lucas’ heroes to make difficult choices, risking death or worse in the name of responding to the immediate threats aimed at themselves and their allies. Then Empire made those choices matter.
They made the choices matter. When was the last time you felt like movie characters choices mattered; where there was not an a priori path that the characters would follow. When was the last time you were genuinely surprised a character's actions or a plot's outcome?