If one knows absolutely nothing about the FBI, this book is a fairly good place to start. But for those who have done a little research, this book covers old ground.
The bulk of the text consists of a historical sketch of the Bureau interspersed with anecdotes on various career paths -- paths limited almost exclusively to special agents. The history is pedestrian. Douglas gives only the basics (which are available elsewhere in far better detail) with a leavening of major cases.
The anecdotes are perhaps more valuable for those considering a career at the Bureau. Want to know how a criminal profiler got his start? Read Greg Cooper's story. Interested in civil rights? Douglas on Frank Watts might be useful. Taken together, these anecdotes provide a passable sketch of life as a special agent. It is not all cloak and dagger. Douglas makes clear that method and hard work solve cases. That, if anything, is the lesson of the book.
But this book is not marketed as a guide to the history of the Bureau. Rather, it is a guide to careers within the FBI. On this score, Douglas's book is a profound disappointment. The overwhelming focus is on special agents. A few pages are given to the support staff, but that information is culled directly from FBI publications.
As for the application process, again, Douglas draws upon free publications. The Bureau pamphlet "FBI Special Agent Selection Process" offers the same information (including the same sample test questions!) in a more accessible format, and is free upon request at any field office. Is the book's price worth advice such as "[don't] be tempted to fudge your answers" (p. 225)? Hardly.
If you are dead-set on a career at the FBI, you will probably buy this book -- if only to have at your disposal every scrap of written information. If your interest is more exploratory, save your money and get the free publications.