Elizabeth Bear succeeds where David Brin failed in Glory Season. What would a woman-dominated human society look like? How would it come about? Why? What, if any, role would males play? How would that society interact with more "traditional," male-dominated human societies?
I don't really know if she set out to answer those questions when she started writing Carnival, but she did a good job of it, anyway. Her vision is hopeful, but she doesn't wear blinders. The characters of the novel move as a marvelous ensemble, the main figures fleshed out believably in their similarities and differences.
Vincent Katherinessen and Michelangelo Osiris Leary Kusanagi-Jones are a couple separated for nearly 20 years by a repressive government that doesn't approve of homosexuality. They are expert diplomats and spies, sent by their government to New Amazonia1 to secure important technology by agreement or espionage. Old Earth and its Coalition are ruled by the Governors, artificial intelligences programmed to control the population and its impact. Everyone lives under constant threat of being declared "surplus" and being "Assessed"—killed. As a result, there is strong pressure to migrate outward. New Amazonia is an attractive planet with an apparently limitless source of clean power, and as such it is a key target for assimilation by the Coalition.
Lesa Pretoria is a strong woman from a line of strong women. In her world, women rule and while men are not slaves, they are definitely second-class citizens. Men are separated into "stud" and "gentle" (homosexual) classes, with stud males sent from their families for fostering and combat training at an early age. If they perform well enough in the Arena to survive, they have a chance at contracts with various women's households. The lives of gentle males aren't explained as fully, but they are freer than the stud males. All men must wear their "licenses" in plain view at all times, and they are seldom permitted to go out unescorted. There is no mention of men owning property or office, or indeed participating in the government in any respect.
Because Lesa loves her brilliant young son, she doesn't want him sent to the Arena. But he doesn't seem likely to be gentle, and she has few legal choices to give him. She's unusual in her world, in that she also has developed a strong emotional attachment to Robert, the stud male who fathered at least two of her three children. She knows that there are significant factions who want all males removed from their world, while other radical factions would turn their society upside-down. She's left to walk a tightrope, trying to preserve her family and society while working for positive change.
I greatly enjoyed the world-building aspects of the novel, and would love to read more of Vincent and Angelo's adventures—from earlier in their careers, perhaps?
Lesa does ask, at one point, why a government that is so focused on population control would be so anti-homosexual. Wouldn't it make sense to encourage non-reproductive pairings? Angelo's response, that people always divide into "us" and "them," especially under oppressive situations, makes as much sense as anything else.
Bear is one of my favorite current authors. I also read her Jenny Casey trilogy this month. Hammered, Scardown, and WorldWired are every bit as good as Carnival. I strongly suggest that you have all three, and a good chunk of time to spend reading them, before you start the first.
1 When asked about the name of the planet, a native says, "What, you didn't think we had a sense of humor?" so I assume that it is intended as a joke.