Widely considered to the best of the trilogy, and I think I agree. A lot of the elements that I, personally, find quintessentially Star Wars come from here—Han and Leia’s relationship, Lando Calrissian, Yoda, hints of Vader, and, of course, the reveal, which is how I was introduced to the franchise. (Never watched it as a kid, although my brother had. Then again, he is a decade older than me.) Han and Leia’s relationship here really struck me this go round; it’s something delicate between two very cynical people who know better, and it’s interesting to watch Han, in his own way (“You could use a good kiss!” comes across not well for me), actually be tender with her. The moment they share when he tells her the repairs are done and he’ll be gone soon—God, she repeats him and just looks at him, and he can’t tell her that he won’t run, because he will.
And, while weirdly paced, Luke’s encounter with his own fear that he will become Darth Vader is one of the shots from this series that actually haunts me; just Luke’s face in the helmet. The whole Dagobah sequence is oddly paced, come to think of it.
Oh, and “There is another” makes me think Leia was going to have a much bigger role, because of course it’s Leia. TVTropes tells me it was initially going to be another sister, which explains tons, of course.