Everybody should read this book. That's all there is to it. Musashi takes the reader into a world filled to the brim with devotion, self-respect, disciplin, honesty and purity of thought. Even though this book was written by and for warriors and samurai, and in a completely different time and culture, it is a remarkabe source of inspiration for selv-developement. Musashi's teachings are concise and to the point. He uses phrases like "you must understand this" and "you must practice diligently" and explains only general, but unquestionable and fundamental, concepts of the Way of the Warrior. These guidelines are not directly applicable in our time and age, but what is applicable are the things this book contains about working with yourself. Striving to achieve improvement on the inside as well as the outside.
It would be a lie to say that this book is a "positive" book. Taken litterally it's about how to become an efficient, albeit enlightened, killer. The value of this book comes from reading between the lines, and let me tell you: Those lines could fill volumes.