Classic feminist sf, or at least that is how it is usually labelled: women live in hi-tech urban enclaves, while men are consigned to a nasty, brutish, short life of scrabbling in the wilderness, worshipping the female principle, as punishment for having caused the (unspecified) world-wrecking disaster centuries ago.
It's not that different from Sherri S. Tepper's The Gate to Women's Country. Sargent's characters are more three-dimensional, but her plot and setting rather less elaborate. I wondered where all the food for the women's cities was coming from; I also speculated a bit about the robustness of the command-and-control mechanism by which the women unleash deadly force on men when they get uppity.
The most extreme example of Sargent's rather inconsistent world-building is, oddly enough, in her erotic passages, where Hero gets it on with Heroine; they are raunchily written yet don't completely fit what we know of the environment - we are told that both of them have had same-sex physical relationships in the past, so the overtones of virginal discovery somehow aren't quite appropriate.
Anyway, I've read it now.