What a fascinating topic! I do love physics and this author has a knack for being able to explain this particular subject well.  A few of the examples were puzzling to me but most were very good as were the illustrations.  He does an excellent job in explaining relativity, quantum physics and the basics of string and M-theory.  I also enjoyed the author's pursuit of his own work in string theory. The discussion  at the end about the possible future of study here was interested though seemed to drag just a bit.  Overall I enjoyed this excellent book and will have to read it again to assimilate what I missed (which was likely a lot).