I'm one of those "saw Star Wars in a theater when I was 10" fans - turning 40 tomorrow (yikes!) - and had long believed there was really just one "split" among fans: OT vs PT. While there was usually some debate among OT fans about the relative merits of each movie, with ROTJ usually seen as a lesser work (unless the fan was quite young when they saw it and/or it was the first of the trilogy that they saw in a theater), I had long assumed that everybody that liked "Star Wars" loved "Empire", without reservation.
As I've read this discussion, along with Anchorhead's "first step into a larger world" thread, I've realized it isn't that simple and, more surprisingly, that my own feelings about the movies are more complicated than I had believed. The points that really hit home for me were:
1) While it's considered a classic now, "Empire" was not universally-loved when it came out; in fact, I think David Gerrold wrote a very luke-warm review for Starlog back in 1980, primarily complaining that too much is handed to Luke in his training and that, in the end, he basically proves that Yoda was right about him being too impatient and angry.
2) Following on from the above, there has always been a group of people who felt that everything after the original film changed/perverted the original feel/story - it's only because there was no internet back then for like-minded people to find each other and realize that they weren't alone that we forget that whole body of opinion existed.
After realizing the above, it dawned on me that, while I'm not quite the "absolutist" that Anchorhead is, I definitely know where he's coming from, and I agree with him in a lot of ways.
The quality of ESB seems to be the real problem - I think it's clear that it's the movie that appeals to us the most as we get older, and it occupies the "golden era" when Lucas had enough money to really "swing for the seats", but it wasn't yet clear that Star Wars was a license to print money, regardless of the quality of the movies. As Zombie points out in his book, Lucas believed, very strongly, that Empire was better than it needed to be for his purposes - he believed that the extra headaches of the schedule/cost overruns weren't worth the incremental increase in box office receipts. I think a lot of us have held out the hope for 25+ years, that Lucas would somehow make another movie as good as "Empire", while, in his mind, he would never allow another movie like "Empire" to be made - it was too painful an experience for him.
So, we have an absolutely fantastic movie, with everybody - the cast, the director, the writer, the composer, the SPFX crew, everybody - doing their absolute best work, and it's all up there on the screen. There's just no getting around how technically and artistically rich "Empire" is, and I just love it. However, I now realize that I only love it up to a point - specifically, the point when Vader utters four of the most famous words in movie history: "I am your father."
Now, I've been complaining for years about "The Incredible Shrinking Star Wars Galaxy" - that the place depicted in the original movie felt big enough for any fan to find room for his/her own ideas to fit into the larger whole. With Vader's famous utterance, that changes, and we never get it back - in fact, the rest of the "Saga" is an exercise in taking a place that felt like it could hold almost limitless stories, and turning it into a place that can barely sustain the one story Lucas decided to tell.
So, I now consider myself a "Star Wars and 90% of Empire" fan, to cover the parts of ESB that expand the SW galaxy, rather than limiting it. After that, as Zombie makes clear, it literally becomes a different universe, one that I don't find nearly as compelling.