Philosophy of the Boudoir is an interesting look at what (possibly) happens behind closed doors. Sade's to-the-point descriptions leave little to the imagination aside from what could possibly occur next. But on a much deeper level, this novel borders that oh-so-fine line between pornography and art; the language, scenes and descriptions are extremely liberal and could be viewed as offensive to many. But the religious (or anti-religious) undertones, the emphasis on the individual and the attention to instruction, precision and detail take Sade's sketchy introductory scenes (with basically little to no plot) into a more developed foundation as the novel progresses. If one can get past the brutal language and over-determination of sexual roles and stereotypes in this book, it would certainly be an eye-opener and a learning experience.
Sade uses repetition to the extremes: Madame, Eugenie and Dolmance are doing the same things over and over again, each time "learning" of the pleasures the exploits can provide and the "tricks of the trade," like how to avoid pregnancy from acts of libertinage, how to keep your actions secret from your husband and what a woman's "duty" in life is. A reader could very easily bore from reading the same action over and over, but one should find it comical that these characters are so into what they're doing that they can never quite realize and achieve this "goal" of ultimate pleasure. The direct language--especially Dolmance's constant "staging" of his lovers--is also comical, because its almost as if these characters were acting out something, wanting their performance to be perfect for an audience, and not for themselves. Again, the "goal" is unrealized. Eugenie is educated in the ways of the libertines, but she is now just one of many who will constantly be in search of that (non-existant) ultimate pleasure.
Again, this book is an eye-opener, not intended for the conservatively-minded. Those with a strong sense of humor will find the repetition and instruction comical, but others will just find it boring and have a hard time finishing the book.