This is a great book. What Hatsumi writes in this really makes you wonder of how to be a ninja. How to enjoy life, and live safe. It really help to read this book if you want the real spirit in Ninja Training. You may not understand everything he means in this book. But you will understand a lot more after a while. And every time you read this book agian you will understand more.
Please buy it.
If what you want are "ninja" stealth and assassin techniques, you're looking at the wrong book. This book is simply an interview with Soke (Grandmaster) Masaaki Hatsumi about warriorship and the *true* meaning of ninjutsu. Being a ninja, a warrior, stretches far beyond merely being an undefeatable pugilist. For those interested in the social/spiritual aspects of warriorship, this is certainly a book you must own. Also look into Shidoshi Jack Hoban's book "Ninpo"--another priceless addition to the martial artist's literary collection.