A blurb on the 1986 paperback edition describes the book: "The war between the sexes has just come to paradise." This expresses the novel's primary theme, that there is a way for the two sexes to live together happily.
Compared to the extremes represented by the invaders (and also in much feminist science fiction of the era), it is a moderate, sensible way.
However, Pacifica, the planetary society which exemplifies it, may not be quite what any segment of the "gender wars" had in mind. It is formally egalitarian, but women slightly predominate in public life, while men remain masters in the bedroom. Pacifica also has a frontier region where the inhabitants are all male and homosexual.
Some of this may have been set up for dramatic effect, in posing the "Pacifican way" against the radical Femocrats and the male-dominant Transcendental Scientists. But it does work within the book...