Gaffer Tape said:
Sometimes I wonder if Han couldn't have been used better for what he was. He was supposed to be the anti-hero of the first movie, and he did a pretty good job of that, but, of course, he redeemed himself at the end of the movie by saving Luke. Empire still had some of that. His original motivation was to get back to that, but it never really worked out. And, of course, in Return, they'd pretty much given up on his character moving at all. So, really, both the sequels wasted that character (as in, there's very little ambiguity in Empire and absolutely no development in Return) as it was originally conceived.

You make some excellent points, Gaffer! I guess by it's very nature, ESB has the other characters tread water while Luke gears up for ROTJ... I think the romance and then parting of Han & Leia serves as their character development in ESB... other than that, they're only there to get Luke & Vader together for the big finale...