I've just finished the first section, titled, like the book, "A Devil's Chaplain." I have to say it was a bit hard for me to read--it causes me to think about things that I'd really rather forget. First of all, he points out how the phrase "devil's chaplain" was coined by Darwin in response to all the cruelty and waste that he found in nature, things that made it impossible for him to believe in an intelligent and benevolent creator God. Things such as the Ichneumonidea larvae which feed inside the living bodies of catapillars--keeping the poor creature alive simply as a source of fresh as a source of fresh live meat. Natural selection in itself is neither kind nor cruel--but it is incredibly indifferent. Especially this is hard for me as a Pantheist, with my tendency to want to idealize nature.
This realization has caused many to reject evolutionary theory out-of-hand, as if reality would conform itself to our preferences. If you don't like reality, should you just stick your fingers in your ears and say "Na, na, na, I can't hear you!!" At the other extreme, some have said that if this is the way nature operates, then it is how human society should operate. This is the infamous theory of social Darwinism, which commits in this case what is known as the naturalist fallacy: that natural=good. But there is still hope.
To quote Dawkins,
There is no inconsistency in favoring Darwinism as an academic scientist while opposing it as a human being; any more than there is an inconsistancy in explaining cancer as an academic doctor while fighting it as a practicing one. For good Darwinian reasons, evolution gave us a brain whose size increased to the point where it became capable of understanding its own provenance, of deploring the moral implications and of fighting against them.
Just because a wasteful and indifferent process lead to our existence doesn't mean we should be wasteful and indifferent. Ironically it was this same process that lead to our ability to speak, and to make art, and to make sense of the world around us. It even lead to our ability to empathise with the plights of others, the ability which is so lacking in natural selection. Science is really strange sometimes.