The two star rating isn't meant to signify that this book on meditation is poorly written, but that it's somewhat deceptively presented as a "self-help" book on how to meditate rather than as what it really is - a book presenting meditation from a very specific theological perspective. I would have had the same reaction if I'd bought a book describing itself as a guide to positive thinking, only to find that it was a tract with prayers to the Sacred Heart of Jesus.
I claim no expertise in the many schools of Buddhism, but I do know that there seems to be some tension between those who view Buddhism as a universally applicable philospophy, and the various religious Buddhists who have very definite theological dogmas. These include beliefs about the landscape of the afterlife (and the pre-life) which one can only accept through religious faith or intuition, or perhaps, some one would argue, through "enlightenment". You can decide for yourself if these voluminous theological details (samsara, bardo, or belief in various gods and goddesses) are essential to the moral, ethical, or practical message of the historical Buddha, or whether they represent a synthesis between his fundamental teaching and other religious and cultural traditions which began very early on. But be advised that in "The New Meditation Handbook" you are not given this choice. Geshe Kelsang Gyatso is a firm believer in a particular theological tradition, and the material on meditation is grounded in this context. If you are unable or unwilling to accept these beliefs, you will find yourself having to separate some chaff from the wheat.