It's a summary of the USA surveillance debacle of recent decades. Such a summary can be useful. For a lot of these tech-y news-summary books, I say "Why would I read that? I followed the news then." But a lot of these incidents had a lot of denials, rebuttals, rebuttal-rebuttals… Yeah, it's nice to see a few months of back-and-forth boiled down to a paragraph or two. I say "nice" as in interesting, but it's mostly bad news. The USA government spies on its citizens. Pundits like to philosophize that the loss of privacy might be worth it to catch terrorists—but in practice, the spying hasn't caught terrorists. It has helped some creeps at the NSA to stalk their ex-girlfriends.
My timing in reading this book was somewhat sad. The author aimed the book to be read and understood by Congressfolks before they decided whether to extend Section 702 of the FISA Amendments Act, i.e., to continue spying. That vote happened recently and Congress (barely!) voted for more spying. You might think that under present circumstances all of Congress could agree it was time to curtail some of the more egregious powers of the Executive Branch, but it ain't so.