I liked Firefly, and I think it was cool, but as Cannoli says, Whedon's extended series tend to wobble. Buffy was thematically inconsistent, Angel had a baby and so did Cordelia (Whedon does like his girls to cry, and when they won't he puts them in a coma), Dollhouse - well.

It was a short run, and it was cool, and it stopped before it could get lame or bad or unfunny or before Mal had to save more prostitutes to prove he wasn't being misogynist to Inara or they made River and Jayne make the hot sex in basements while escaping from bug ladies. Enjoy its cool, self-contained perfection, and go watch Serenity to round it off.