Dr. Penrose has written an incredible tome outlining his primary research area spanning his entire professional life.  As a result, one can expect a detailed, penetrating analysis of some of the most difficult and interesting portions of physics.<br><br>I do wonder, however, about the intended audience.  Very few will actually be sufficiently prepared to understand much, if any, of the book.  Even many professional mathematicians will have difficulty unless their training includes considerable work in differential geometry and related areas.<br><br>As a result, I suspect that this book will join "Gravitation" by Thorne, Misner, and Wheeler, gathering dust on the shelf, as one of the least read physics books of our time.