A fascinating book. I got a copy when it first came out (I was looking for a replacement today) and have re-read it several times. I hope it's not too much of a spoiler to say that it shows, among other things, that there is no experiment that could distringuish whether or not there is a God without that God's intention to be experimentally verifiable. This has implications to both epistomology and theology that I think have never been properly explored: it means that the question is not just one that has never been settled scientifically, it is one which _cannot_ under any circumstances be settled scientifically.
I can only fault it in assuming a bit too much background for the most likely reader -- but certainly not anything that a serious reader cannot overcome.
A philosophical must for technically-minded atheists, agnostics, and for believers.