I finally got around to watching this film. I bought Firefly and Serenity on DVD a few months ago with the intentions of watching the series before the film. Within the first two episodes of Firefly I was astoundingly hooked. What a great concept for a show. I could really see it being a viable future for humanity, ie. sure there is greater technology but the problems we have now still remain. I loved the cast and their interactions with each other. Not sure why so many are talking about bad acting...I thought they all did a great job. There was also the element of campy one-liners, but I feel it contrasted nicely with the exceptionally dark aspects of the story.
I'm glad I watched the series first as I felt at home watching Serenity. I already knew the characters, their attitudes and temperaments so I just got to enjoy the story line as an extension of the show. The CGI effects were top notch and fit in seamlessly with the filmed scenes. I also especially enjoyed the old school camera work with imperfect framing and plenty of zooms--nice to see that idea come off the shelf. As much as I liked this movie, I wholeheartedly believe that I enjoyed it more because I knew the series. I'm sure I still would have liked it having not seen the show, but there would have been many unanswered questions concerning the choices some of the characters make in the movie.
It's a real fucking shame that Fox royally screwed the show by preempting it and airing episodes out of order because the plotline of Serenity would have made one hell of a season 2.