I really don't understand why this score is getting such bad reviews.
For myself, I was enthralled by the general sound of it. (Indeed, a lack of woodwinds--I never quite registered that before, which is pathetic, but now I find it to be a nice little touch, perhaps something to do with evil Alliance metal rather than warm happy Earth That Was wood. (No idea.))
This score pleases me the most in its wonderful imitation of the original 'Firefly' music, without outright copying it. Solo cello in place of the show's violin, and the Western edge to the music, although a bit toned down now. It peeks over the edge of atonality, and appropriately so. As for these so-called nonexistent themes? The themes are more motifs, and they weave around nicely *I* think. In any case, I found it satisfying, even in the slow creepy tracks (which are simply necessary if you want a good climax—duh).
I also love that Joss seems to have been so involved with the score. Just saying.
And another thing--who dictates that themes for female characters have to rest with a voice? (Or a flute for that matter. And besides, I think I recall female voices at some point, although I could be making that up.) Sheesh! Pianos are our friends, even when synthetically funkafied, I think. For River's theme is very pointedly that forlorn piano bit that surges over the rest of the score rather deliciously, at points.