I have just finished reading this excellent book.
I am not a Ninja - this is the first thing I should say - and I have no intention of becoming a Ninja. However, I will recommend this book, heartily, to anyone, because it is a thought-provoking and useful book.
The author sensitively relates a series of experiences and his reflections upon these, thereby personifying the Ninja: and showing that anyone - albeit with the right attitude, with the correct sense of perseverance and ability to reflect, and with the discipline in his or her approach to self-development - can become a Ninja.
However, whilst anyone with the right potential CAN become a Ninja, the experience Martin relates also shows that becoming a Ninja is far from easy. I admire the author's humility as well as his skill, intelligence and diligence in his pursuit of Ninjutsu.
Most important to readers such as myself is the fact that useful lessons can be applied to a variety of scenarios, professions, people and places. This Ninja flexibility is the greatest lesson. The central section of the book, covering the use of the five elements to approach a variety of life's situations, was for me just one example of something practical and enlightening.
Some may find the more martial elements more intriguing; others may discover something of value in lessons about espionage, gadgets and devices; and others may value the lessons in stealth or endurance. Whichever one of these suits your interest (though it may be several or all), and whether you choose to apply the lessons or simply enjoy the story of a travelling Ninja, I think that you will enjoy this book.