I enjoyed it, but I tend to like the idea of hidden societies, codes, and ordinary people getting sucked into the extrodinary. I wouldn't recommend it unless you can seperate reality from Fiction. My wife and I got into a few discussions about the book where she felt I was attacking the church when all I wanted to do was explore an idea in the fictional universe. The challenge is in the book bouncing around the line of "reality". Since the setting is "today" and the concepts could be true, it evokes a deeply emotional response in many people. I can see why it caused a stir during its release.
Just keep in mind that it's fiction, and you'll probably enjoy it. I gave it 3 out of 5 over on Amazon. It was a nice break after finishing up The Reality Dysfunction (all 3 of them).