Have not seen the movie or had a chance to read Dawkins' books, but I have seen his talks and read some of his online material.
But I'm taking a larger view of the phenomenon of atheists speaking out against religion. Thirty years ago atheism was hardly spoken of, by anyone, and societies like that in the US went merrily along imposing more and more religious overtones upon the populace as a whole. Especially in recent years, with the overt coming out of gay people demanding to have their rights protected, there has been a rise in American fundamentalism that certainly appeared to have as an end goal the Christianization of most secular institutions and activities, including government, education, arts, sexuality, and so on. If you read the Discovery Institute's Wedge Document, you see an outline for theocracy, and given their serious attempts to insert their propaganda into schools, something had to be done to shine a light.
Since atheists make up a small part of the population, it is IMO necessary that spokespeople for atheism have no choice but to be as loud and in-your-face as possible, else risk not being heard at all. If theists find their words insulting, at least they have heard them. Christians of all people, looking to their roots, ought to know that at the beginning of a religion or a movement, someone is going to have their feelings hurt.
The vast majority of atheists and agnostics are not anti-theists, that is, we don't have any desire to make people give up religion, or God. What is desireable, and should be desireable for theists as well, is that secular life not be controlled by religious considerations. Theists should desire this because, although you may be a religious majority in your society today, tomorrow another religion might become the majority, and it would be a theocracy not in the interests of the minority.
Many religious still treat atheists as a suspected class of people - look how much time some of your politicians put into making sure you think they are fervent Christians.
Watch this video, and note this woman's point about Barack Obama's
atheist mother:
http://www.youtube.com/watch?v=-4wQfQtpDAc