Overall the book was good. Hitchens is really an excellent writer, easy to read and never goes too cerebral. This I found to be positive mostly because it made the book very accessible while at the same time communicating some very complex ideas. Generally speaking I enjoy Hitchens' style. He's very matter-of-fact as well as putting forth a certain acerbic surety that gives the book a powerful and distinct voice.
That is not, of course, to say that the book is without its flaws. As was stated in various individual chapter reviews its often lacking as far as scholarship. That's also a side effect of what Hitchens did to make the book more accessible. Hitchens isn't really a historian or a scientist; Hitchens is a Journalist, and that's the style that works for him. Its a visceral, easy to pick up style that excludes nobody. However, due to his lack of background as a scientist or historian the arguments often lack alot of the punch that proof might provide, and the very limited citation I would also consider a weakness.
The biggest weakness though, i'd probably say is that it tries to tackle too much for its scope. Its not a long book, only about 280 pages, but he tries to cover 3 holy books many world religions, and arguments both for and against them. This is really just too much for anyone in my opinion. I fully expect Hitchens to write more on the subject in the future, but I'm really hoping he'll choose a more focused method in his next attempt.
In the end it was enjoyable. In most cases I tend to agree with Hitchens which actually made it difficult at times to to be critical of him, but I think in the end I did a fair job with it overall. Please feel free to criticize or comment. I'd really like to know what people think of the final product.