I think that reading this book could potentially ruin your life in the best way possible.
You thought you were just going to be an ordinary Buddhist, perfect in your flaws, meditating now and again to calm your mind, meeting cuties at group meditation. That was until Trungpa, the ultimate bull in your beautiful China shop, came thrashing through. He kicked in the windows, broke your tea set, and turned around with this crazy smile on a nostrils-flaring face, and you knew things would never be the same.
Chögyam Trungpa Rinpoche is an invaluable teacher in my life. If it were not for him I think I would likely stagnate all the time in my quest to be a good Buddhist. There is a kind of raw energy, openness, directness and contemporariness that I simply don't see elsewhere. He is not trying to be polite or proper, nor to make life easier or "less stressful". His books are not for anyone who is seeking relaxation or stress relief through meditation. He wants to wake you up, and in this text he is going to burn your house down just to make sure you get out of your bed.
This book contains powerful lessons for anyone wanting to awaken in Buddhist practice. For all such people, this material can shock you off of your cushion and into real-world interaction with the teachings. There is a kind of energy, a kind of just-do-it mentality, a you-can-do-it-ness, and a what-are-you-waiting-for-ness to this book, that makes me feel like I'm excited to be alive.
You're going to need actual instruction, for which I recommend finding a living teacher or some other texts by the same author, such as Training the Mind. But for those who are already into Buddhism and especially Tibetan Buddhism, you should read this book at least once --- kind of like that occasional dip into a cold mountain lake, you might just feel awake and alive in an I-can't-explain-it---just-see-for-yourself kind of way.