I'm on the fence about my rating for this one. If it were on option, I would probably give it 2 1/2 stars. It's a thought-provoking book, and it took me a while to read it because I often found myself staring off into space pondering the mysteries of the universe. (I consider that a positive). On the negative side, I thought the arguments presented here were uneven. Dawkins brings out everything he's got against religion, and some of the arguments are weaker than others. Why spend so much time talking about how there is a correlation between atheism and high IQ, for example? Come on, Professor, we know correlation and causation aren't the same thing (a third factor could be the cause of both, yada yada yada). Respect your reader a little more and get to whatever you consider the real arguments to be, because surely that's not the best you've got.
Dawkins presents his arguments in two main sections, one arguing against the existence of a god or God (in any form - no passes for deists or agnostics here) and the other against religions themselves. I found the God section more interesting, though it seemed to come down to saying that the existence of a god or any external supernatural force would be an extremely low probability event, and the origin of life in some other as yet undefined fashion would also be an extremely low probability event, but the non-god way is less improbable, so it wins. Since science doesn't yet have an explanation for what caused the jump from no-life to life, I don't know how we could know how high or low the probability of that would be to make a mathematical judgement. We are missing some key pieces of data. Dawkins finds the theistic answer inelegant, since it's an infinite regress in that you would still have to explain where God came from in the first place. Certainly that's true, but I don't think this quibble is quite the Q.E.D. moment Dawkins was looking for.
I found the case against religion less interesting overall. The evils done in the name of religion aren't news to anyone, though Dawkins does bring out some interesting less publicized Biblical examples. He also points out that even if there are good points to religion, it doesn't make any difference if there isn't actually a God. But the converse is true, too - even if religions do a lot of horrible things, if there is a God you can't avoid them, so the social impact of religion one way or the other doesn't make the case. It's also in this section that Dawkins must have decided his book wasn't controversial enough, so he takes tangential side-trips into the debates over abortion, assisted suicide, stem cell research, and how the Amish educate their children.
Overall, this was an interesting read, but I suspect it probably hasn't changed too many minds.