I got the book cheap just to see what all the fuss was about. I haven't read the second or third books, so I can't comment on them, but as for the first, unless you find a blowjob to be particularly shocking I don't really get what the big deal is.
The primary appeal of the book seems to lie in the psychological implications of bdsm
, not in pushing the limits of sex acts for their own sake. It's a case of, forgive me, "more than meets the eye."