I also remember walking out of ESB in 1980 utterly shaking in pants wondering what just happened to my beloved characters from Star Wars? As a kid, this movie did not sit well with me, and the irony is how I did a 180 years later and realized how great it was.
I was 8 when I saw ESB, as I remember turning my head when Han cut open the taun-taun guts! I will always remember when Yoda first came on screen and acted like a wack-job, and the audience actually laughing thinking this was some sort of muppet joke, and at that point the movie could have lost credibility, until Yoda turns out to sucker not only Luke but the audience!
And of course the whole cave scene went right over my head at the time, as kids like myself really thought Darth Vader was there on Dagobah! After that sequence was done, I turned to my brother and said, "What just happened????"