I bought this book because although my own art (Krav Maga) does not stress locks and controls they have always fascinated me.
I was not disappointed - the text is very comprehensive. Virtually every lock I have ever been taught or seen demonstrated is in this book, along with many that were completely new to me. The descriptions of the techniques are very good, and accompanied by helpful tips and details of possible counters. The book is clearly structured, starting with conditioning exercises and then working through the different types of control (finger->wrist->elbow->shoulder etc...). A major strength of the writing is that the author never belittles the difficulties of applying a control in a real situation, especially when compared to striking.
I would recommend this to any martial artist interested in deepening their understanding of this area, reagardless of their own style.