Basically one form of attack, with two ways to execute it. Maybe with this you will be successful in 80% of your combat encounters. Maybe it's too simple to rely on. Unfortunately, my knowledge is based on theory only.
From the theoretical standpoint, I think this book is lacking alternate strategies. If there is any transferability from the left jab / right cross in boxing to the left lead / right stab espoused in this book, then, theoretically, one would be setting oneself up for a counter if one ONLY used the technique recommended by this book.
But what do I know? I have not been in a knife fight. My only experience can be based on unarmed combat (street and dojo), supplemented by theory. If you can rely on your right cross to get you through your unarmed fights pretty much of the time, then you probably will like this book, and you may very well be effective pretty much of the time because it's based on the "right cross" / "big gun" principle ... set 'em up with the lead hand, and attack with the rear power hand.
BOTTOM LINE: I'd probably resort to this approach since it is based on realistic experience, the technique is VERY BASIC, and I believe in the author's experience. BASICS are usually the most effective, and it would take a very extremely trained and experienced "sophisticated" fighter to beat a very extremely trained and experienced BUT BASIC fighter.
I gave it three stars because it was average as a book, but as another thing to add to my arsenal, I would give it a 4