In this sense, I am defining "Good" as meeting the "objectives" he sets out to achieve in writing the book. By "objectives", I mean the objectives I believe he had - not the one *he* states he has. In writing this book, I believe Dawkins is aiming at *two* main audiences. The first audience is the uncommitted/loosely committed, nominally falling under a particular denomination, but who is overall unconvinced and open-minded. With this audience he is encouraging them towards the "non-believer-in-God" end of his religiosity spectrum. He is using the fact that peoples opinions are highly corellated with associated opinions (eg. the opinion that Religion and the state should be as separate as possible is highly correlated with the view that religion is "bad"). This is excellent in terms of persuasive writing, even if it is under contention that the world will be a better place with more atheists.
The other main audience I believe he is aiming for is the committed (or zealous) atheist. With this audience, he is affirming their beliefs and strengthening the arguments across a swathe of the spectrum. He is also arming them with numerous "sound bites", analogies and references that they can use in arguments with the loosely committed - *especially* in the context of the loosely committed being a minority amongst his peer group.
He rightly concedes that aiming to the audience of hardened religious or rigidly theological, or even rigidly philosophical part of the spectrum is a lost cause. Unless one takes that strict logical positivism is the only kind of logic that is valid, his logic is neither convincing nor watertight.
So I have to concede that he easily achieves his aims in this book, and his desired audience is captive and extensive. It is just that I am neither in his desired audience, nor do I think success in his writing goals will make the world a better place. Quite the opposite in fact.