It is an interesting book, to get an insight into esoteric Tibetan Buddhism.
It's a short book, so many of the concepts aren't explained in detail so it's like a sci-fi story at times.
It's incredible to me how much contempt for Christianity and Islam is shown by the author, who is a Lama and is supposed to be an enlightened being. How can I trust a person who speaks about Christianity in a serious book, while being clueless about it? It seems that many of these Western Tibetan Buddhists do that all the time. Just explain your practice and outlook, there's no need to insult and lower other paths (especially when clueless about them), it's sad that we even have to talk about this.
He constantly stresses that they don't need a God as a reference etc., then speaks about celestial Buddha forms with multiple arms and invoking a golden form of Lama that radiates energy into your forehead, throat and heart...
All in all, it confirmed some of my thoughts about these forms of Buddhism - they are mostly a mish-mash of traditional Theravada Buddhism, Tibetan folk pagan religions, yogic and tantric methods with primesses of cult-like Guru/Lama worship.
In my modest experience, Theravada is 'real' and most effective Buddhist path, with no bells and whistles.