I first found out about Darrel Ray at Skepticon IV in November:
My friends from Kansas City gushed about his book, The God Virus, and the quality of his character. I found his talk both entertaining and informative - I have a layman's interest in human sexuality (beyond just the interest in sex most humans have, whether they acknowledge it or not) and the survey describing sexual satisfaction before and after deconversion was something that hit home.
When the book was finally released, my friends and I decided to start a book club, featuring his book as our charter book; as such, I didn't actually get around to reading it until my flight to Washington D.C. for Reason Rally and the 2012 American Atheists Convention. Three days later, on my flight home, I closed the book, having finished it, and I'm here to tell you: this is an intensely interesting and relatable depiction of sexuality in humanity.
I've seen most, if not all, of Darrel's presentations on this book - the duck sexual physiology, the "rubber band" theory (which I find to be a fantastic metaphor for the dynamics between religious sexual upbringing and natural sexuality), the "50-0-50" theory - and, for those who share my situation, I can tell you that there's still more to be found in this book. Darrel does a good job, in my opinion, of answering how, despite the fact that sexually-restrictive individuals (monogamy, no sex before or outside of marriage) will tend to reproduce less, such sexual ideas came to be the dominant sexual ideology in major world religions, and he gives great information on the sexual practices of existing human societies, demonstrating the value of accepting and working with, rather than against, harmless sexual urges (as well as much more).
What made this book the most significant to me, however, were the personal stories. Coming from a religious background myself, and having dated a girl from a very conservative and religious background, the stories of sexual frustrations and guilt told by stories submitted to Darrel and reprinted in his book struck a very personal note, and I found it to be extremely cathartic to know that I was not the only one (in fact, such an experience was the source of my "A Healthy Fear of Hell" blog post a week or so back).
Bottom line: great book, and you'll know more about sex (assuming you're not a clinical psychologist specializing in human sexuality, of course) coming out than you did going in. Pick up a copy today.