The text goes into the brain like a buttermint, but I'm not sure there was a reason to make it book-length. It was obviously rushed to publication - I spotted at least 2 mistakes, an error in the title of the movie Zack and Miri Make a Porno (the book thinks her name is Mimi) and a misspelling of Adderall. Sales likes to keep a descriptive adjective for her subjects and stick with it - poor Nick Prugo whose only defining characteristic is, according to Sales, that his hair is thinning. Alexis Neiers gets a "squeaky" voice (I do love that Sales documented what I hope is every time Alexis yells at her mother for talking.)
But who could fault the publisher or Nancy Jo Sales from capitalizing on this story? It's an enjoyable if depressing look at celebrity-stalking culture, starring teenagers who are unaware that their narcissism is showing. Sales fills out the story with speculation as to why and how this kind of culture grew and affected Valley denizens (and non-Valley denizens), but it's never a mystery how the kids (allegedly?) did it, and it ends up being cringingly sad how they all try to deny it and rat each other out.
In other words, I'd recommend it for a plane ride, or you could read the vanity fair article.