I've seen the Trilogy, in whole or part, close to 2,000 times, and everytime I see a scene again, I pick up something I hadn't seen or realized earlier. The Trilogy's richness in detail is what makes it great.
To dt's point about his friend never having seen II before:

In the VHS days I made a tape of the deleted scenes (copied from the "Saga" version shown on TV) and kept it in my office. I worked for a very large company, and there were dozens of hardcore GF fans in our building. I'd offer to show them the tape of the deleted scenes if they hadn't seen the "Saga" version. It was always a pleasure to watch the looks of astonishment and pleasure--they'd discovered a hidden treasure.