Bottom Line: If you know the terms and tenets of Buddhism already, this book will be an excellent in-depth treatment of the philosophy. If you don't know the terms and tenets already, this book will be a very difficult read.
NOTE: This review is NOT meant to start a philosophical argument. This review is simply about the book, and the contents of the book from a reader's (as opposed to a practitioner's) perspective.
I do not closely follow Buddhist teachings; I knew a little bit about Buddhist philosophy, and I picked this book because I wanted to know more. As I started reading the book, I felt like I was entering a lecture hall where a famous and knowledgeable person was speaking eloquently on a subject he knew well, but that I didn't know anything about. At all. I am quite well-read, and I have a great vocabulary, but I found out rather quickly that my experiences thus far did not prepare me for the words and concepts I encountered in this in-depth treatment of one school of Buddhism, as practiced by one of the acknowledged masters of the philosophy.
HOWEVER, I'm also stubborn by nature, so I regarded this as an opportunity to learn and to grow. After reading the book through once, I noted some connections and descriptions later in the book that helped me understand certain terms early in the book. SO, re-reading the book, and visiting Wikipedia a few times, has helped me illuminate what the author was saying in such a matter-of-fact way.
On that note, one distinct positive aspect of the book is how kindly and lovingly the author and the translators treat the material. It is manifestly obvious this book was created out of an intense desire to share Tulku Urgyen Rinpoche's unique, rich, lived experiences with Buddhist thought and the Buddhist way of life. Even to a non-practitioner such as I, this effort was a smashing success.
Overall, the book was a growth opportunity for me, and I'm glad for that. I do not know whether I'll buy Volume 2; I may re-read Volume 1 (again). I would suggest the potential reader consider whether he or she already DEEPLY understands terms like "Samsara," "Karma," "Nirvana," and the deeper tenets of Buddhism; you will encounter all of that stuff in this book, and it is treated as if you already know something about them. If you believe you might want to study up on those things first, I would recommend a Buddhism primer (which is NOT this book), or some online study first; then open this book, and prepare for a beautiful explication of what you have only started to learn.