I'm only about 100 pages into the book. So far, it's very interesting. My only complaint is that I don't find Professor Penrose's explanations of math very easy to follow. I'm not a mathematician, although I had a pretty good background in calculus, and I've never had any trouble with understanding math when it's clearly explained. For example, Penrose's explanation of complex numbers was a bit confusing at times. However, I read David Poole's appendix (in his Linear Algebra text) on the same subject and found it much easier to follow. This could be just a matter of personal learning style matching pedagogy, but Penrose, albeit undoubtedly brilliant, is not the best match for me as a teacher.