I've seen the trailer for the movie, which certainly looks promising. I'm an interesting sample in this case, because I still haven't actually seen the Firefly TV series. The scheduling was bad for me when it was on TV and -- I understand from my friends -- it suffered from little details like being shown out of order. It's available on DVD and is one of the things I've been planning to get around to, just as soon as I find a supply of round tuits that I'm not using.
So here I am, long-time science-fiction fan, walking in clueless. We'll see how many clues I have when the movie is over.
Here's the synopsis for the film from the publicity folks:
Joss Whedon, the Oscar -- and Emmy -- nominated writer/director responsible for the worldwide television phenomena of Buffy the Vampire Slayer, Angel, and Firefly, now applies his trademark compassion and wit to a small band of galactic outcasts 500 years in the future in his feature film directorial debut, Serenity. The film centers around Captain Malcolm Reynolds, a hardened veteran (on the losing side) of a galactic civil war, who now ekes out a living pulling off small crimes and transport-for-hire aboard his ship, Serenity. He leads a small, eclectic crew who are the closest thing he has left to family -- squabbling, insubordinate and undyingly loyal.
And you can find the trailer and production notes here.