What better read for the Christmas season than a book tearing apart all religious belief? Dawkins is one of the best science writers I've encountered, and he puts his insight, his lucidity, and his wit to good use in this book, which I will argue is essential reading for everyone, regardless of faith or lack thereof.
Dawkins doesn't hold back here. His hope, as stated in the introduction, is that this book will convert believers into atheists. That ought to spark fear in all those whose faith rests on the dubious foundation of willful ignorance. For those interested in critical thought about religion, though, this book is essential. I don't share Dawkins's hope. I'd just like to see people engage these ideas openly and honestly, and the results will take care of themselves.
All of the usual arguments for the existence of God are addressed here, and each is dismantled in turn. Dawkins argues that while God's existence can't be disproven, there are no good reasons to believe He (or Allah, or Ganesha, or Zeus, or the Flying Spaghetti Monster) exists, and a number of good reasons to believe He doesn't. The benefit to approaching this in a scientific way is that the reasoning is transparent--if there's a flaw in the argument it will be observable and addressable, not just dodgable via some version of "just because" or "faith."
I have two gripes with Dawkins's approach here. First, I don't think he gave enough attention to the belief-as-choice concept. He brings it up and summarily dismisses it, which it deserves when judged merely on its strengths as an argument, but which falls far short if Dawkins seriously hopes to sway the reluctant religionist. Since he doesn't lay out the reasons why beliefs can't be chosen (which has been covered at length by others, such as W.V.O. Quine and J.S. Ullian in The Web of Belief), he leaves the subject open for a dodge, undermining the rest of his work.
The second issue is in Dawkins's overuse (in my view) of emotional appeal regarding the religious indoctrination of children. He considers it immoral to push a child into metaphysical convictions she isn't prepared to properly consider, and while I'm sympathetic to his position, the repetitive evocation of "Oh, the children! The children!" felt like pandering.
In all, I think this book is an important work in religious discourse. The dangers of religion become more apparent all the time, with radical Islamists slamming planes into buildings and radical Christians causing their own brand of mayhem, such as Dubya claiming God told him to invade Iraq. Time to reassess the whole enterprise.