My sister is an atheist and even she couldn't get through this book. She didn't like the way he acts as though he speaks for all atheists everywhere as if there were a unified doctrine of atheism, which would kind of defeat the purpose. She specifically cited his statement to the effect that atheists abhor tradition, which is certainly not true of my sister, who sees most traditions as a matter of culture, not just religion.
Anyway, I haven't read it but thought I'd give you her opinion, just in case it's helpful or something

Ohtori_tsuki