At first glance this appears - and is - a handy little book explaining many espionage and intelligence terms. It is wonderful for concise summaries, biographies and explanations of sometimes complex intelligence machinery.
Very useful in helping in studying intelligence texts (academics can sometimes throw in data without comment), so a quick grab at this guide is useful, and it includes some of the oddest facts. So far, it's a sort of Dangerous Book for Boys and Girls. So long as you let it stay that way; fine. Beyond that, there emerges some problems:
1. Some data (spellings and dates) are simply wrong. Double-check dates and spellings. But, the general subject matter is right (see caveat 3 below). Also, as there are only photographs (and few of those), diagrams would help explain some organisations. The complexities of Soviet bloc intelligence really need illustrating.
2. Some common phrases and terms are simply missing.
3. When explaining some history (that of the Profumo Affair is notable), while the narrative is clear, at times there creeps in a powerful judgemental tone. This brings doubt on a work which looks like an encyclopaedia (more objective than a book; avoiding controversy) but passes judgements. Be very careful to check other accounts. Also, when the views are clearly moot, no references are provided. Given that the foreword is by ex-5er David Shayler, one of the most controversial British intelligence figures in recent years, this does not help unsupported judgements. Was Shayler a good idea for what should be an objective little book?
On the whole, a nice dip in the intelligence ocean for the lay-spy (5 stars on this level) but out of its depth when coming to more complex and unsupported arguments (2 stars on this). On balance 3/5.