I'll keep my gripes with the story out of it, since this is merely a novelization and I can gripe about the story at the movie review.
As a novelization of the movie, it serves the purpose to tell you what happened. For those that have seen the movie and want to relive it - this does the job in a decent manner. Mostly.
There are additions, alterations and subtractions in this book. Something I dislike very much is the apparant necessity of adding in vulgar language to the book where it simply did not exist in the movie. If the movie can do without, why not the book?
Additionally, there are several chapters in this book that simply do not happen in the movie. Granted, the first few are necessary for those without a background in Firefly - and are even welcome reminders to those of us that have, but the rest take away from the actual story. As written in novel form, much of the rising emotion that generally comes before a tense moment, simply fell flat due to over telling.
There is little-to-no detail in this book. I can't tell you how many times I got tired of the author referring to a characters appearance as if everyone already knew what kind of visual traits they possessed. River's "little sister look" and Zoe's "why did I marry you look" get real tiring to read through.
The more intense scenes in the movie were terribly translated to the page. Continuing his lack of descriptions, the author could only muster weak scenes that the movie displayed most profoundly.
As a book - terrible.
As a novelization - not very good.
The $7 you spend on this book could be better spent on popcorn for another trip to see Serenity.