It was good, but, ironically for a book about math I found myself sometimes wishing there was just a touch more math in it. This delves far more into the history of the subject, which is interesting and useful in its own way.

It's always strange, however, to read a math book and get the vibe that the writer is afraid too much math will scare off his readers. I think if it had just a touch more, it would have been perfect, but after reading the book once-through I was still confused what the function R(primes) was, only knew that it existed and helped predict primes using the zeta function zeroes as a correction, which seems a shame when it is so important to the subject, and I had to go to another book to figure that out in more detail.

Read this if you are interested in mathematical history and like the math kept simple.