My degrees are not in literature...so although it's tempting to analyze this title in the literary context of Spinrad's other outstanding works, I'll confine my comment to my own profesional field (social sicences):
Any other master of speculative fiction (Ellison springs to mind) could MAYBE have crafted this humorous yet at its core dead-serious examination of the balance of power between the two Human sexes. But leave it to Spinrad to set the stage so masterfully by first immersing us in the TOTALLY BELIEVABLE Earth-colonized world of Pacifica (you do the linguistics) where the "55%/45%" balance of power we currently enjoy between males and females in the professional and personal world is reversed: females are JUST THAT TAD BIT UP in both professional and personal power, yet males feel fully empowered in business and politics and proud in their personal lives to partner with powerful women.
Spinrad is very careful here. He doesn't skew the balance of power enough to really upset anybody here/now/today...but he does tip it JUST enough to make any careful reader of either gender THINK.
Into this ever-so-slightly-disrupted, just-enough-that-you're-already-THINKING-about-that-balance-of-power world Spinrad injects two groups of power-hungry outworlders: a militant female-dominant culture and a militant male-dominant culture, each bent on "intellectually colonizing" Pacifica.
No spoilers here, sorry. Suffice to say that a generous handful of UTTERLY BELIEVEABLE, three-dimensional characters who are in, of, against, for, not-of, not-for, and a-plague-on-both-their-houses are followed through all the thorny personal and relationship decisions that this political clash among otherwise peaceful Humans must always occur s when socio-sexual worlds collide.
Sounds like a lot to handle for one "science fiction book," neh?
Heh. Read it and see.
Spinrad will blow your mind every time. (Not quite a spoiler: If you like this title, try "The Void Captain's Tale." THAT title will blow your mind so bad/good/indescribable you just might oughtta put in for a week's vacation before you open its cover.)
The ending provides no easy answers...but when I first encountered it as a Young Human almost 30 years ago, this book gave me that "1/4 turn" on the usual viewpoints society and the media present to us that is SO essential to adult social/political/psychological thought.
It packs no less of a punch to me than it did when I first read it in high school than re-reading it now after several social science degrees and two decades of immersion-experience as a military wife as well as a social scientist of various very-strange-to-me societies around the world.
As Pope put it so quotably, "The proper study of Mankind is Man." There is no better place for young folks to start than Norman Spinrad's "A World Between."