Firefly was just OK as a show, it didn't really do anything special though. It was a pretty good show, but doesn't live up to the hype and adoration it receives. I think it came out right on the cusp of where sci-fi became mainstream and films/shows started producing stronger story and character driven content, so it gets an unwarranted heavily rose-tinted view from fans.
*noisy ducks for cover from fan wrath