I wish I could agree with you, for one good reason and one bad one. The good reason is that I read Mating at a susceptible age—roughly the same age the narrator was at the time of the novel, which is to say in my late 20s—and felt wildly vindicated in my own glib, pedantic, super-opinionated, and somewhat defensive grad-student response to a world far less compliant with totalizing theoretical models than my education had led me to anticipate. Karen (we learn her name only in this new novel) wasn't just a hell of a character; she was my idealized self. She was jaunty and smart-alecky and threw around high-faluting academic jargon with the right shade of disillusioned but nonetheless affectionate theatricality. Naive as hell but possessed of great panache, she let herself be fazed by nothing—not by being stranded, broke, in Africa; not by crossing a very scary desert with only two donkeys for company; not by the phenomenally gorgeous body of the African woman possibly competing with her for the attentions of the founder of their utopian cooperative, Nelson Denoon, a development specialist. (Please don't call Denoon an anthropologist; being a Norman Rush character he naturally draws the finest of leftist distinctions and disdains anthropology as a tool of the ruling classes.) She was for the likes of me what Nancy Drew was for the 9-year-old set.
The more ignoble reason for wishing to agree with you? Yours is the contrarian position called for at this late stage in the reviewing cycle. No one else has thought this novel superior to Mating; in fact, almost all the reviews have been negative. You do us the great service of bringing out the novel's overlooked strengths. This is a novel of astounding intelligence, a social novel of the sort that everybody's always calling for. It weaves together in a far-reaching way an encyclopedic knowledge of daily life in one Botswanan city with many completely original (and some less original but nonetheless powerful) ideas about marriage and colonialism and espionage and the role of monotheism in developing or stymieing the Third World, and even the First World—to list just of few of the topics in the book.
You're also right about Mortals being structurally more complex and ambitious than Mating—though I strongly disagree with your assertion that Mating was desultory and diaristic. Mating took the form not of a diary but of classical, that is to say, Augustinian, autobiography. Our heroine never once manifested the ignorance of the future required of the diarist. She knew all too well what was coming, and she never let us forget that it was catastrophic; the general strategy of the book was to locate us deep within one of modern fiction's more entertaining and irresistible voices, that of a latter-day Moll Flanders, a feminist adventuress game for it all but prepared for none of it.
Given all this, it is with guilt and dismay—and the dark suspicion that I'm being one of those annoying readers who gets so stuck on one book she can't bring herself to appreciate the next—that I have to say that I found Mortals almost unreadable. As you say, this novel is just as intelligent and perhaps more interestingly plotted than Mating. (At any event, it's more like a Conrad novel than like something written by Defoe.) But the very quality that made Mating a total page-turner—voice—dooms Mortals to unbearability. Ray, who dominates every page of this very, very long book, is, quite simply, a bore. He has an exceedingly keen way with adverbs (he calls one ambassador of his acquaintance "transactionally odd"), but he seems incapable of not finding every last thing about himself interesting, and Rush seems incapable of not indulging him in this solipsism.
Critics have dwelt at length on Ray's mind-numbing uxoriousness, but I was just as put off by his endless perorations about every shade of love and rage and by his manipulative relationship with his gay brother, his underpaid servants, his brute of a boss. (I was amused, though, at how prophetically Bush-administration Boyle seemed to be.)
If, before reading this novel, you'd spent the week rereading Mating and reading Whites, his short stories, for the first time, as I had, then you would have started to see how repetitive Rush has become. Many of Ray's observations about the ironies of life in the Botswanan expat community will seem familiar to those who have read the previous two books, also set in Botswana, where Rush actually spent only five years (and that was 20 years ago). There are the bored wives, the out-of-it ambassadors, the murderous sun, the traffic, the impossibility of knowing where you as an idealistic Westerner stand with the locals, the predations of capitalism, and the stupidity of socialism, etc.
Last but not least in my litany of what made this book hard to slog through is the notebook-emptying quality to Ray's account of his spy duties. Rush did his homework, all right—he's better than le Carré when it comes to giving away the secrets of tradecraft. And yet the book—at least the first half of it—is heavy with the burden of what James Wood would dismissively call "information." There was equally as much discussion of the mechanics of work and life and sex in Mating but such was the wit of Karen's voice that I never minded. In fact, I remember laughing out loud when I came to a sentence about Karen and Nelson taking a postprandial stroll through Tsau to check out the goat-repelling fences. When did you ever see the words "goat-repelling" (or whatever it actually was) and "postprandial" together in the same sentence? Everywhere Karen went she seemed to make up fresh words for a new kind of world, as if she were Adam in the Garden of Eden. She was a charmer, that girl. Ray is not. And sadly, that makes all the difference.