Joseph Goldstein's latest book is basically a very good synopsis of his personal journey in the Buddha-Dharma and in his own practice. It reiterates many of the themes and principles that he has discussed in previous books and introduces some relatively new ones (e.g., relating to Tibetan Dzogchen, for example). For someone new to Buddhism, this might be a helpful or even an inspiring book. More seasoned students might detect, as I did, a subtle uncurrent of ideological assumptions.
The idea of "One Dharma", as Goldstein presents it, is not entirely coherent.
For one, the suggestion that there is "One Dharma" emerging in the West is at odds with Goldstein's stated assumption that the different traditions of Dharma will continue to exist distinctly, even in the West. If that is so, then there are Many Dharmas. Historically there have been many cultures and many different kinds of people, and for that reason, the historical existence of Many Dharmas has been a good thing. The West is multicultural so one would expect and hope to see Many Dharmas flourishing here.
Nobody can argue convincingly that Buddhism will not evolve and adapt in the West. Likewise, it seems obvious that cross-fertilization of traditions is, to some extent, a sign of Buddhism's adaptability and relevance. However the idea that "One Dharma" is emerging and that "One Dharma" is a leitmotiv of "Western Buddhism" seems naively idealistic.
The idea of "One Vehicle" as taught in the Lotus Sutra is the most obvious doctrinal precedent for Mr. Goldstein's basic idea. In spite of the Lotus Sutra's apocalyptic message, many Dharmas continue to flourish down to the present era. So assuming the Lotus Sutra's principle of "One Vehicle" is coherent, and that Goldstein's "One Dharma" is a reiteration thereof, the real message here is not that there is--or will be-- just "One Dharma" in an historical or doctrinal sense, but rather, that all Buddha-Dharmas have, in the final analysis, a single savor and a single intention.
If this is Goldstein's point, I agree wholeheartedly. Even so, I wonder why he would suggest that "One Dharma" is a special feature of the "emerging Western Buddhism". How is Western Buddhism so special if all Buddha-Dharmas have always been been "One" -- that is to say, grounded in the same basic principles? In this sense, Western Buddhism is nothing special. It is the same old Dharma expressed in a new language, with a new set of metaphors and rationales. It is no more or less "One Dharma" than any previous era of Buddhism.
For these reasons I think the book's title and ostensible message of "One Dharma" emerging in the West are much ado about nothing. Granted, the different traditions are interacting with each other here and yes, it is generally a positive thing for Western Buddhists to supplement their main studies and practices with forays into other traditions and other ways of contemplating the teachings. But for reasons already stated, I think it would have been more honest to title the book "One Thread" -- since there certainly is a single thread of definitive truth running through the various teachings and traditions of Buddha-Dharma.
If "One Dharma" is supposed to be a special feature of the historical evolution of Buddhism in the West -- and not of the Dharma generally -- Goldstein has spoken a bit hastily. It is too soon to say that there is only "One Dharma" in Western Buddhism, unless that "One" is the same as the "One Vehicle" of Asian Buddhism. If "One Dharma" is not just a statement about the unique, holistic intent of all the Buddha's teachings, but an observation of what Western Buddhism is or should become, then some kind of personal ideology, or an assumption about what makes Western Buddhism "special", would seem to have reared its unruly head.
To respect and understand this book, one needs to understand something of the author. Since the 1960's Joseph Goldstein has been practicing Buddhist meditation. His goal with the Dharma is alleviate suffering in himself and in others. He does not believe he will write the seminal book on Buddhist theory or the perfect koan or answer everyone's questions about the Dharma. However, if you are a serious seeker and are attempting to understand something about this wonderful phenomenon Buddhism, which is growing so rapidly in the United States, this book will help you a lot. It is a beginner book. Yet, it is also a book which will give long time practioners a chance to reflect about the meaning of their practice and the nature of the Dharma.
Over ten years ago, I, suffering from a deeply painful and debilitating bone disease, came to Joseph to find a way to live with severe physical pain. Joseph helped me with compassion, with joy, and with humility. He will always remain my core teacher.
Reading the other reviews, I can say, you will get what you look for. If you are look for scintillating Zen wit, try Genpo Merzel Roshi (a living zen master), for philosophical wisdom, try Trungpa Rinpoche. If you are looking for a teacher who will give you a framework from which to work while you sit on the pillow, you can not do better than Joseph Goldstein.
Good luck, and, please, persevere. The world needs the merit of your meditation practice.