Dr. Nida's Path to Rainbow Body provides a wonderful initial overview of the marvelous teaching of the Yuthok Heart Essence, the principle spiritual teaching employed in Tibet for the training of physicians in continuous use in Tibetan medical schools since the 12th century, the time of Yuthok Yonten Gonpo the Younger. This book gives a brief but thorough introduction to this unique method of the doctor's essential inner training that must precede and complement the vast external learning that must be mastered over many years of medical school and early practice.
This book does indeed provide an "overview," with a couple of paragraphs each on such diverse topics as tummo and dzogchen. It does not contain any original texts except for the 7 page song of Yuthok Nyingthig. There are 4 commentaries on the root text and this book devotes a page each describing the commentaries. There are no practices here, and on its own this book seems to have little value. If the author is your lama then I expect it might come in handy.