The Good Spy

So I don't know if I should give this a rating. It's very difficult to rate some non-fiction. Do you rate for the comprehensive knowledge the author has on the topic, or do you rate for pure enjoyment alone? The book was well-researched and full of facts- 5 stars. Unfortunately, for pure enjoyment , 3 stars. So as I'm writing this, I have it as a 3 star book, but I'm going to change it to a 4 to meet the 3 & 5 in the middle.