Bound to be a topic of high interest.  This slim volume contains a lot of information about a variety of spying technologies, the purposes for which they were developed, and the historical/political contexts in which they’ve been used.  The main critique I have of the book has to do with its organization — the publisher’s efforts to jazz things up with cool graphics have led to a layout that includes random side-bar paragraphs stuck in where they interrupt the flow of other information.