I gave this book three stars for one reason: it is the book I would recommend to someone if they want a protection dog and have no business owning one.
Ms. Flynn's definition of a "dog for protection" is a pet, be it a Daschund or a Doberman, that has a stable temperament and passable obedience. Yes, you read that right, that is all there is to her definition. With this definition in mind, the book offers some training techniques (some of which that may still be employed by people training pets), but to say the book provides "detailed information" and is a guide to make your dog "protective and alert" is creative puffery at best and false advertising at worst.
Much of my time reading this book was spent appreciating the sheer entertainment value of some passages (for example: "A stranger seeing your dog move along beside you on a loose lead might even jump to conclusions. That dog, he might decide, looks as if he's had attack training. Better leave that one alone."). Entertainment value aside, this book actually does contain pearls of wisdom and sound advice; for example: it emphasizes the necessary commitment of real protection/sport training, has good tips on selecting a breeder and pet trainer, and even mentions the concept of plateaus in training.
The biggest criticism of books on the subject of training "protection dogs" is that the book arms the reader with just enough information to be dangerous - this book does not do that at all. At the very most, this book arms the reader with the most basic skills and knowledge necessary to being a responsible pet-owner.