While it is hard keeping the characters straight initially, eventually they become more detailed and recognizable. It's worth the effort to get to that point as this book, while somewhat exaggerated, shows the polarity that has grown up in swaths of rural America. It also shows both the effort and rewards of working on a farm.
Paretsky is very liberal for an American, as shown in her more famous detective novels, but her bias shows less in this novel as the majority of the characters are portrayed sympathetically, no matter what their philosophy. The exceptions are the fundamentalists, and as someone who grew up in the Bible Belt, she isn't too far off the mark with them either.
I would recommend this book highly, mainly because of the narrative flow, a property all too rare in modern novels.