In the past couple of years I have read Genuine Happiness: Meditation as the Path to Fulfillment (2005), Contemplative Science: Where Buddhism and Neuroscience Converge (2007), and Embracing Mind: The Common Ground of Science and Spirituality (2008). These are very good books, but this new one feels to me more general in its appeal than earlier books. It would be nice to see his work reach a non-Buddhist audience, but judging by the lack of promotion on the part of the press, I don't see that happening. In my opinion, it's a missed opportunity on their part - and a loss to the culture at large.
Mind in the Balance was written for his daughter, who has been a Christian for most of her life. She wanted her father to write a book that could help her improve the quality of her inner life and mind, a book that would be useful to everyone interested in a better quality of life, whether they are Christian, Buddhist, or something in-between.
The book begins with four good chapters, though brief considering he has written whole books on the topic, on the science of meditation, it's origins, and it benefits. He cites many of the most recent and promising articles on the benefits and uses of meditation in medicine and psychology. For the general reader, this is great introduction that may lead some into his more academic books on the subject, including the two mentioned above.
The remainder of the book is devoted to twin chapters on meditation techniques and the philosophical/psychological theory behind the practices, bridging a variety of religions, not just Buddhism and Christianity. There are ten of these practice/theory pairs, ranging from simple mindfulness of breath to contemplation on the emptiness of matter and finishing with a chapter on being mindful in our daily lives - the idea of "meditation in action."
I'm sure that Buddhists from different schools might quibble over some of the subjective states Wallace associates with various techniques, but that is a matter for experts. The lay reader should simply keep in mind that Wallace writes from a Tibetan Buddhist tradition, which is only one of several variations on the teachings of the Buddha.
Likewise, I'm sure that some Christians (and those other faiths) may not recognize their own religion in some of these practices, which is sad. So much of Christianity (especially Protestant, but also Catholic) has been divorced from the contemplative practices of the monks and nuns who spent lifetimes cultivating a direct relationship with their conception of the divine. This book offers a way back to those traditions in a non-denominational practice - and it may contribute to a post-modern Christianity (as advocated by the Trappist monk Father Thomas Keating in the form of Centering Prayer).
Overall, this is a highly recommended book for meditation novices and experts alike. The ten practices and theories presented, along with the scientific research on meditation, form a compelling arguments for living a life informed by meditation. And as a side note, I suspect that this book can contribute to a better understanding of how Buddhism and Christianity will co-mingle in the West in the coming decades.