Damasio's book will be somewhat tough sledding for the non-specialist, but it's still a good book and worth sticking with to the end. Using Descartes's famous dictum as a departure point, and through a discussion of current theory and detailed case studies, he demonstrates the intimate relationship between the brain, mind, and body.
The case studies of sensory agnosia were very interesting, especially the one where the patient had apparently lost the functioning of the part of his brain that stored the awareness of one side of the patient's body, to the point where the patient had no awareness or perception of that half at all, and even denied that he even had a problem with it. There can be no clearer demonstration of the fact that our consciousness and awareness depends entirely on that 3-pound, convoluted mass of nerve cells we call the brain.
As someone with a pretty fair background in the area myself (I did a master's and almost completed a Ph.D. in psychobiology) I can vouch for Damasio's command of the scientific and technical issues and details (notwithstanding that fact that Damasio is both an M.D. and a Ph.D.) so he has a good command of the medical issues also. The book is very well written, although not easy, but Damasio does a fine job of explaining the more difficult ideas.
One further comment, I read one review that was critical of Damasio for supposedly misinterpreting Descartes's dictum, "I think, therefore I am," and then spent the whole review discussing Descartes instead of Damasio's book. The reviewer also stated that because of this Damasio lacks scientific objectivity. Since his comment is itself a good starting point for discussing the most important aspect of Damasio's book, I thought I'd write a little more on it here.
Whether or not Damasio's interpretation of Descartes dictum is wrong or not, (and from the other reviewer's disjointed discussion, that itself isn't very clear), this is a minor detail, since Damasio simply uses this as a point of departure and from there on the vast majority of the book is devoted to a discussion of the neurological and brain issues, not to the technical details of the philosophy of mind-body dualism, for which there are already plenty of other discussions out there (having read many of them myself).
However one should precisely interpret Descartes's famous statement, Damasio is completely correct in pointing out the most important aspect of Descartes's idea--that the mind is fundamentally different from the brain itself and that one needs a dualistic theory to explain the separation of the apparently immaterial mind from the more material body--is wrong.
Although echoes of this theory can still be seen in modern philosophy, and were an important influence on idealist philosophers that followed Descartes, such as Kant, and even continue to have an influence on modern neo-Kantian theory and other thinkers, the advance of modern neurobiology has shown that these theories are fundamentally wrong.
Since we're on the subject--and to be completely fair--I will that say that one aspect of Kant's theory is quite accurate--that the mind is actively involved in organizing the data of the senses--and that ideas about the external world could not exist unless there were corresponding mental capabilities and constucts to match. Our understanding of sensory information processing and of advanced cortical abilities certainly show that the brain has evolved in a way that reflects the need for specific capabilities to enhance our survival in a dangerous world. Kant's idea that there are inborn mental faculties that allow us to form ideas about the external world isn't so different from this idea, and in that sense, Kant was right. (This would have been a good point for the other reviewer to make, but he got lost in the trivial details, and failed to see "the forest for the trees" (as he himself incorrectly said of Damasio)).
Anyway, returning to Damasio's book, this is well-written book on a fascinating aspect of modern neurobiology, and which has profound implications for western philosophies of idealism and dualism. Although not an easy book for the non-specialist, it's worth the effort.
I have one final suggestion to make, and that is you might want to read Michael Gazzaniga's more general introduction to neurobiology: "Nature's Mind: The Biological Roots of Thinking, Emotions, Sexuality, Language, and Intelligence," before tackling this one. It's also an excellent book and you'll have a more well-rounded understanding of the brain field which should stand you in good stead to tackle this book, or any other brain-oriented books, after reading it.
