I don't think it's far superior to Buffy, but I also have all seven seasons.
Firefly is an excellent series and Serenity is an excellent movie. I bought the series over the summer and watched it in less than a week. I bought the movie on Tuesday, watched it again, and then watched his commentary last night. His explanations for why certain scenes exist, or why they are done in a particular way made me realize just how good Joss Whedon is.
Eh. Firefly got canned right as it was starting to hit its stride. The TV show had its moments, but wasn't that great overall.
Serenity was vastly superior.
"For one thing to live, another thing must be killed. God, or whoever is responsible, deserves respect for creating such a system. It reveals that we cannot take all matters into our own hands. We need only to focus on doing our best--a simple, yet profound way to live, is it not?"
Serenity was a great movie, but Firefly was also a great show. In some ways, I enjoyed it more than Farscape.
Rosalina: But you didn't. Robert: But I DON'T. Rosalina: You sure that's right? Robert: I was going to HAVE told you they'd come? Rosalina: No. Robert: The subjunctive? Rosalina: That's not the subjunctive. Robert: I don't think the syntax has been invented yet. Rosalina: It would have had to have had been. Robert: Had to have...had...been? That can't be right.