I got this book from a friend of mine who I've talked with religion about on and off for the past 15 years or so -- while not super religious himself, he's the son of a Baptist minister, and a very thoughtful guy (and one of my best friends), so I've been looking forward to reading this. This book is not for the faint of heart -- it's a scathing critique of religion's basis in faith, and in particular of tenets of Islam that Harris believes make it unethical for Muslims not to wage war on non-Muslims.
He also argues that we're in a period of extreme relativism, where moderate, tolerant positions are as effectively damaging as extreme positions. I don't believe all the arguments here, and he clearly takes much out of context from the Koran and the Bible both. But I think it's worth reading at least so that we can all talk about these ideas more in the open, with better critical thought than we have to date.
Anyway, I had some strong emotional reactions to this book; not sure I think it's a great book, but interesting, anyway, and useful for tidbits of controversy to throw out at the dinner table. :-)