I've read it, and was unimpressed.

Dawkins is a good scientist (or at least a good popular science author), but his understanding, and even knowledge of philosophy is highly limited. I read many philosophers, and have taken several classes on the subject, and there are many arguments against the existence of God (as well as for), but none of them are mentioned by Dawkins. The only argument that he seems to be using is the Flying Spaghetti Monster argument, which I see as a very weak strawman argument: it does disprove the existence of deities like Zeus and Thor, and perhaps the original Jehovah, but not the philosophical concept of God, around which all of religion revolves, and due to which we are so drawn to religion.

Philosophy aside, I believe that the practical side of the book is also lacking. He argues that moderate religion is harmful since it paves the way to fundamentalism, but I would argue the exact opposite: people have an innate desire for religion (it stimulates a very specific part of the brain, as demonstrated by neurological studies) that they will want to satisfy, just like their sexual and romantic urges, their desire to lead or follow, and their desire for substances like drugs and alcohol (note that prohibition doesn't work). Moderate religion allows people to satisfy these religious urges without causing any significant harm, and providing many psychological benefits. In the absence of moderate religion, fundamentalist religions (like radical Islam and certain American Evangelical churches) or even cult-like religions such as Scientology rise to power, embraced by people who feel that something is missing from their lives and can't get it elsewhere. A classic example of this is the rise of radical Islam in European countries: young people raised in entirely secular households, with their religious desires unfulfilled seek religious fulfillment from mosques, operated by radicals with a political agenda.

Even if you see no metaphysical value in moderate religion, you should at least consider it as a 'vaccine' of sorts.

But I think that Dawkins knows all this full well. The problem is that such an idea will not sell books as well as radical Atheism. 'End radical religion' isn't nearly as attractive a slogan to angry young Atheists as 'Death to all Religion, the root of all evil'.