Lousy. Both the math and the literary parts are wanting. Like many current books, this seems to have lacked a proofreader. Lots of repetition, mistakes (Einstein is called Eisenstein once) and the author tends to go into random excurses, discussing Hindu theology and Ledeerman's dementia for no apparent reason.
Halkin is an excellent writer and a deep thinker. However, it shocked me when he said in one of the last essays that he is an optimist. The big thing lacking from all his works is any sense of joy. I also wish he would write about where he stands religiously; there are a lot of bits and pieces but I have little sense of what he believes.
A mixed bag, but mostly good. On the positive side, it is comprehensive, interesting and particularly fun when the author derives lots of ideas from tiny facts. On the negative side, this could have used much more editing: lots of repetition, saying one thing in one sentence and the opposite in the next. Plus the font is ugly and hard to read.