This took me a while to get through, not because it was bad, but because there is a lot of information and material to get through and understand (and I had to take multiple breaks to get away from the realistic, logical arguments and read something fun).
Overall, I think this was very well written. As an atheist there are a lot of arguments I can get behind. At times I felt that Dawkins' language was a little too strong and often he came off as demeaning and mean. And while it was in no way his intention to be nice regarding religion, I think his rude attitude didn't help persuade people (an unfortunate example of the privilege of religion that Dawkins points out in the book, but is no less true).
This is quite a heavy, dense book, however, so as the only other book I have read by Dawkins is The Greatest Show on Earth: The Evidence for Evolution, I wasn't prepared for this book. It is a good book to read if you actually have time to sit down and think about the material.
I really enjoyed some of the later chapters, especially the chapters on morality and possible origins of religion.
This is a good book for people looking for a powerful perspective on the unnecessary existence of religion.