I read _Stiff_, which I borrowed from a friend and reread it again for book group recently (didn't quite finish it the second time). I read _Spook_, which I bought, for book group, altho I forgot to _go_ to that book group meeting, which was sad.
It was inevitable I would buy and read _Bonk_, altho this is the first time I've bought Roach new in hardcover.
Roach's books are all pretty similar: she gets really into her topic (dead bodies, the afterlife and, now, sex). She travels all over and interviews people. She inserts herself (ahem) into the storyline by telling you not just what her interviewee said, but some of where he or she said it: over lunch, and what the reactions of the servers were. This is often uproariously funny because, after all, these are kind of paralyzingly taboo topics to get into in public.
When I read _Stiff_, I knew a little about the topic (primarily from _Dead Men Do Tell Tales_). I knew very, very little about what was covered in _Spook_. But _Bonk_, let's just say I was a little embarrassed how much of the subject area I was familiar with. Which is not to say I didn't learn a ton; merely to note that I'm pretty sure _some_ of my readers know even more about the subject area than I do (and not by a little, either) -- they might learn considerably less.
I think the chapter I was most impressed with, by the sensitivity of the handling (oh boy), and because it was completely new to me, was the chapter about the doctor who treats and studies people with spinal cord injuries and other CNS damage. I also really liked the section with Kim Wallen and primatology, the silly detour on pheromones and so forth.
Should you read it? Oh yeah. You should read everything by Mary Roach. Of course, most of my book group strenuously disagrees with me -- they don't much care for her two previous books and I don't see this one changing their minds. I do sort of wonder where she's going to go next. Religion seems like a reasonable next choice.