The movie was paced very well, there was plenty of action in the beginning and end, although the middle dragged just a little. Each character also got their bit of the action, and of course, River gets a lot of action. I'm rather disappointed with the smaller parts that Inara and the Shepard get, especially the latter fellow, but at least he had some great lines. The characterisation was good too, all the actors slid back into their roles very naturally.
The "Mr. Universe" character seemed a bit of a gimmick to me, perhaps even a deus ex machina, which is uncharacteristic of the Firefly motif. He's a little too sudden and a little too pivotal to the plot for my tastes.
Wash's death was quite dramatic and meaningful. Apparently, he's the character with whom I identify the most, and I do love his dinosaurs. The people at the theatre (and it was pretty crowded) literally gasped when he died, because it came out of nowhere. I was so saddened that I had to go to the washroom. When I came back, they were getting ready for the dramatic fight scene where Simon and Kaylee would get to be romantic and then River could save the day.
As usually, it's the actors and the characters who drive this movie. I can't complain, the dialogue and the delivery is pure Firefly and great to see. My dad, who has not seen an episode of Firefly, said the movie was "great," and he is very critical of movies. I was surprised by the turnout, but one of the unique things about Firefly is that, even though it's science fiction, it doesn't focus on the science part of the fiction, it focuses on the humanity (similar in the way that the new BSG does), which helps it draw in a much larger audience.
Now I hope they just don't make a sequel. . . . .