The basic premise of the book is that morality is not under the purview of religion like it is often discussed. He feels that morality can be decided by science. There are various states of being that are empirically better than others and once we admit that, we can move towards those states. He feels that there is a moral landscape with various hills and valleys and humanity's goal is to one day make it onto one of those peaks.
This is a fascinating argument. I have always found it hard to believe that "Thou shalt not murder" is carved into every hydrogen atom in the universe however, if you look at morality from the perspective of human well being it allows for there to be moral truths without there being moral laws created by some higher power or universal constants.
However, this theory is intertwined with some incredibly acidic discourses on religion including what borders on a personal take down of the director of the National Institute of Health at the time the book was written. He then uses that segue into how hard it is for him and his "new atheist" friends. In the edition of the book that I read there is an afterword where he responds to a bunch of criticisms of the book. This would be acceptable and perhaps even an educational look into his ideas if it weren't for a bunch of comments at the beginning where he basically complains about famous people giving his book bad reviews without reading it.
I think that the primary thing that I will take away from this book is his original idea and the long debate that it sparked about whether one can believe in objective morals in this sense without believing in objective aesthetics as well.
Overall, I would give this book an 81%.
