My plan with this work was to read only the introductory essay by Simone de Beauvoir and The 120 days of Sodom. The introductory essay by de Beauvoir is great, but in the end, after reading de Sade, I think she is taken in by de Sade's efforts at self-delusion.
As for de Sade, I finally decided to read him because he has been hailed as a forerunner of transgressive literature. De Sade is turned on by the act of transgression but he is hardly a forerunner of such works as Crime and Punishment, Lolita, Requiem for a Dream and Fight Club. He is a forerunner of a lot of creepy writing on the internet.
I thought that I would get a perverted erudite 18th century version of the Story of O. What I got was sadistic pornography, which I suppose should not have surprised me.
There are theoretical parts to his writings, and they hold some interest in seeing how philosophical ideas and education in general can be perverted for self-justification of the unjustifiable. However, Lolita is much more interesting for this despite the fact that it is fiction. I don't find his ideas interesting except in this regard, because they quickly descend into internal inconsistencies. Fundamentally, he is just trying to hide from himself that even by the low low standards of an 18th century French aristocrat he was still considered a monster.
De Sade writes well and is well versed in literature and philosophy, but his writing is not really even erotica it is just very erudite and screwed up pornography. I don't think that the difference between erotica and pornography is a difference in intent, which is in both cases to arouse. Nor do I think that the difference is in the sex acts depicted. The difference is in the way the individual is depicted. In pornography the people are objects and they are defined by their sexual characteristics. In erotica the characters are defined more broadly and their eroticism comes from the fact that it is subjects engaging in sexual acts. De Sade is a clever pornographer, but that is all.
Whether to read him becomes then a simple question of whether he turns you on. To which I say: "Ick. No."