To summarize anything I might say below - this is an incredible book. Mind-blowing. If you're reading reviews (as I do) trying to find the few people who didn't love the book so you can have an "unbiased" view, very good for you. (that's how I choose books, usually) My unbiased view is this - I *very rarely* give out fives. This is one of the few books that deserves it.
Matt Ridley explains in the epilogue of The Red Queen that half of his ideas are probably wrong, just like those of Freud, Jung, and many others. But this common-sense attitude, projected onto the evolution of reproduction, is EXACTLY what about this book makes it so incredible.
Ridley is grounded in a reality unfettered by religion, social science, social mores, or really any sort of external "moral" influence. (Not that he's the antichrist or anything - he's just not letting standard social concepts influence his ideas.) A few people who don't usually want to accept reality (ultra-conservatives) will hate this book. Fine. If you believe in creationism, go elsewhere. Otherwise, read this book! This is not a political or an ideological work - this is a scientific text on human evolution, and how it has been influenced by sex.
I have been able to RIVET people with discussions of facts and theories from this book. It's the best money I've spent on a single book in quite a long while. And in case I sound like way too much of a suck-up - I haven't read any of Ridley's other works, not because I haven't bought them, but because I looked through them in bookstores, and every one I looked at seems either uninteresting, wrong, or awful. But this one is GREAT!