This novel is a roller coaster. Very sexual and intimate at times, very inappropriate and challenging at times. The premise itself is a little difficult to swallow, because we have to watch a woman be dominated by a man. However, when the novel is flipped in the second half, Severin becomes the feminized slave, dominated by women. Ultimately, this leads to the final embarrassment where Wanda dominates Severin in the last way she can: She cuckolds him for a better lover and humiliates him in the process.
But that's not the end of the story. The end of the story comes when Severin's emotional embarrassment causes him to realize that he did it to himself by forcing their relationship into a battle of power. He ends by saying that as it stands, women are not being empowered enough for relationships between men and women to be healthy by default. He concludes that men are dominating women in other ways, and that the suffering he endures is caused by his desire for power.
Ultimately, the book is a argument for sex positivity and female empowerment. The use of (sometimes gruesome) sexual scenes helps to drive the main point of the novel home. The first dilemma of feminism (at least in this novel) is that in their personal lives, men seem willing to play power games with their wives instead of allowed their wives to be equals and partners.
The humiliation and "suprasensual" sexuality make the novel esoteric, because many people, if not most people, will not enjoy the awkward, embarrassing moments of domination and submission. This is a story about sexually brave people learning the difficult truths that their sexualities contain.