I've seen about three Firefly episodes, not in order. So I have a faint idea for the characters, but zero sense of plot. Most of what I have I gathered second hand from the rabid Firefly fans (RFF), of which I know bajillions. You'd think that bajillions would allow a show to stay on the air, but I digress.
First off, "Joss is a Bastard." This has been a common thread of most of the reviews I've read. This was a common utterance after Buffy episodes, and some Angel ones as well. High praise. I'm pretty sure the reason for this particular sentiment for this particular movie is because he kills off a Named Character. Thats the only thing I can think of that makes sense in the movie. There may be other things that might cause that if you've seen the entire run of Firefly. I haven't.
This is not a movie that I'll have to see again and again to make sure I got all the subtle bits. In fact, I don't particularly need to see it again (at $5+ a viewing that is. DVD is something else). The plot was good, the universe has potential though it did leave out key bits, and there was a blessedd lack of Bug Eyed Monsters[1].
The lack of a BEM in this SF movie adds several points into the plus column right there. I have a serious weak spot for films that are based in space and do not involve things either trying to eat humans, or blow humanity back to the stone age and beyond. Battlestar Galactica (old and new) fits this bill. Star Wars fits this bill. The most recent Star Trek movies do NOT fit this bill, which is why I haven't watched the newer ones. Plain old human problems in space. Ahhhhhhh. Too bad the setting is so bleeding expensive to film in.
I do have to say that there is more interpersonal tension packed into one episode of Battlestar Galactica than Serenity. I know it is hard to build to that sort of tension without having a couple of hours of setting to build it, but it did come through like that. I did get a sense of the characters in the end.
There were a few pieces I particularly liked. First off was the opening shots. It looked like one long no-cut shot, and that's difficult to do, and completely missing from modern film. Great!
The second thing was the opening sequence. The Serenity making entry to a planet and things go boink that aren't supposed to go boink. The ship clearly was using atmosphere to bleed orbital energy and you could see the plasma. Cooooool.
Third, unsteady cam usage was minimal. There was a sense of the camera-man swinging to shots, but nowhere near what BSG uses. Nice.
The science wasn't as objectionable as it is in other films. They never get into what the FTL technology is, or even if the universe needs it. EVA stuff was at a minimum so that particular peeve never surfaced. No kill-o-zap guns, just plain old projectile weapons. I know that space films have to bend physics to do what they do, but there are limits[2].
In short, this movie was, "not too bad," to use the Minnesotan.
[1]Bug Eyed Monsters: This is my name for a phenomena in SF films. It decends from the pulp days when an actual bug-eyed monster was the main plot device. These days the BEM can be represented by a Giger monster (Aliens), microbes (Species), inexplicitly hostile aliens (Jugement Day), or Things Man Was Not Ment to Know (Event Horizon). Or more genericly, Plucky humans struggling against an Unknown and Powerful Foe.
[2]Limits: We all have our areas of knowlege that won't let us bypass them. For me it is unreality in space. The biggest offenders are movies based 'now' but involve space. Such as Deep Impact. I happen to know quite a bit about our space capabilities and some stuff is just impossible. And stuff like that can't be suspended. There was a run of Mars movies a couple years ago that had laughable physics.