For those who are studying and practicing Buddha's Tantric teachings this book explains everything. Geshe Kelsang Gyatso doesn't hold any information back. He is a very pure and qualified Tantric Master. His kindess and love for all living beings is shown through his clear and profound explanations.
This book has immeasurable benefits with many practices that can lead us to full enlightenment. Especially for those who have had Tantric empowerments and are able to rely fully on their Spritual Guide.
Tantra is traditionally kept secret, is considered an advanced Buddhist practice, and is much misunderstood by those who have not experienced it directly. Tantric practice requires the personal experience of initiation and/or empowerment directly from a teacher who provides an oral transmission of the teachings and secret mantra. Absent readiness, we will not encounter a teacher who can transmit this knowledge. Absent the transmission, we can read about Tantra, but will have at best a purely intellectual, rather than an experiential, awareness of the practice. Most often, though, those not karmically ready for the teachings simply don't get it.
That said, anyone can gain from an open-hearted attempt to absorb as much as possible from genuine resources. Your experience of any book on Tantra will depend in large part on your personal development. For those who are starting or have started on the path in particular, a description of the path in vivid detail will prove invaluable. For those nurturing a curiosity about Tantra, further reading will help you determine whether the practice is for you.
One caution. Geshe Kelsang Gyatso and his New Kadampa Tradition centers have been involved in considerable controversy concerning disagreements with His Holiness the Dalai Lama about particular practices. The presentation in this book, however, appears to be in line with accepted teachings of Tibetan Buddhism. It is always advisable, particularly in tantra, to reflect on the importance of the teacher-student connection and be guided by one's genuine and undiluted devotion.
May the Dharma benefit you and all sentient beings!