I know it's kind of pointless to review some of the most re/viewed movies in history, but I'm working my way through the original Star Wars trilogy on DVD and I haven't seen them in awhile, so I'm putting down some thoughts anyway.
Something that struck me while watching Empire is that every time I see a Star Wars film, I catch something I missed the previous 50 times. I generally chalk this up to my not paying close enough attention or forgetting that I actually caught it the last time around**. But I also think, begrudgingly, that Lucas is a little smarter than I give him credit for and the first three movies are more complex than they seem.
The novel thing this time around for me occurred during Luke and Vader's first meeting in Cloud City. I never noticed that Vader isn't trying to turn Luke to the Dark Side to join him and the Emperor. He wants Luke to help him overthrow the Emperor and they'll rule as father and son. And then that sets up all sorts of weird shifting alliances and intrigue between the three of them...the Emperor is trying to play Vader and Luke off of each other, Vader is trying to keep his true goal a secret from the Emperor and might have to kill Luke to do so, and Luke's trying to fend off both of them and keep his own secrets (Yoda, his sister). I mean, it's not The Godfather, but it's not bad.
** This happens to me all the time, especially with shows like Law & Order. I can't remember a single episode from start to finish, which means I can watch them over and over again and always be surprised about what happens at the end.