[I received a copy of this book through NetGalley.]
This book provided an introduction to part of what you can find on the "Deep Web". If you don't know anything about it, or just a few things, it will give you some starting points which you can use to then find out more. If you already know what there is to know, probably the book won't be useful, though.
Divided in two parts, "Cybercrime" and "The Dark Net", it introduces some of the basic ideas and concepts. What's the Deep Web and what can you find it it. Who's more likely to use the Tor browser and other tools to remain anonymous (not only criminals and terrorists: activist and people who fight for their rights do need a place where they can share information without being silenced by their governments). Examples of cybercrime: drug-selling websites, child sexual abuse, or simply places where you can buy regular items with Bitcoin. Interestingly, crime appears to be the least spread activity, and a lot of people who use the 'Dark Web' do so for reasons that do not go against the law. All in all, it's a good reminder that a tool is never as good or as evil as the hand who wields it.
The book also provides examples of some of the most well-known leaks, uses of virus or worms, and DDoS attacks. Nothing new to me, but something that will be useful to neophytes, without drowning them under a deluge of information—and not as biased as one may have expected: all in all, the author tried to present various sides of the story, so to speak. (Of course, keep in mind that what's in the book is only the tip of the iceberg: the most juicy bits are the ones you will -not- find in a book.)
I'm not rating it higher because in the end, it didn't bring me a lot of information I didn't already know. But I don't doubt it will be more interesting for other readers.