What made it great to me was that it was a craze for nerds. It made things like science, space travel, robotics, computer programming, etc., all seem cool and fun. It wasn't like other crazes involving celebrities or rock stars or sports or clothing, or other things that made the popular kids even more popular. It was a real, bona-fide craze, for us nerds!
The other thing I remember about it is that it lasted so long. Star Wars was playing in theaters for something like a year, or more. It seemed like for a long, long time, any time you wanted to see Star Wars you just pop on down to the theater and it was there.