There's quite a bit of information about her on this up-to-date Wikipedia entry, so I needn't add too much to it. I must confess that I usually liked her short stories better than her novels (though that's true of many sf writers), and her critical writings better than her fiction. Even her classic story "When It Changed", about a planet where all the men had died off centuries before, leaving women to carry on quite competently, is uneven; Russ herself said that she got the opening paragraphs quickly, as if by dictation, and then had to "finish the thing by myself and in a voice not my own." It shows, I'm afraid. "When It Changed" was the first thing I read by Russ, and it left me ambivalent, but then a friend referred me to an essay in which Russ argued that SF gave more scope to action by women characters than mundane fiction does, using examples of standard story modules with the sexes reversed: "Alexandra the Great," for example. That was what hooked me on Russ's writing, though I did track down and read all her fiction too. If I had to whittle down my library to its core, I'd certainly keep How to Suppress Women's Writing, (Texas, 1983), Magic Mommas, Trembling Sisters, Puritans and Perverts (Crossing Press, 1985), and To Write Like a Woman (Indiana, 1995), though I'd probably also keep her fiction because most of it's out of print and hard to find.
One of the notable traits of her fiction is its anger, still unacceptable in women's writing to this day. A favorite exchange of mine comes from The Two of Them (Putnam, 1978), in which a female agent violates the Prime Directive by deciding to rescue/kidnap a brilliant, talented girlchild from a planet where girls and women are not permitted to be brilliant or talented.
"Which arm shall I break?" says the female jinn [Irene, the agent, from the perspective of the girl's father].I still find this funny, though many of my friends disapproved. Russ's writing helped me to come to terms with my own anger, for she struggled herself with the taboo on women's anger and (even fantasized) violence, and wrote about it brilliantly, as in her essay on man-hating in the collection Amazon Expedition (Times Change Press, 1973, pp. 30-31).
"If you break my arm, I will not be able to write the visa!" shouts 'Alee.
The female jinn says, "I will not break your writing arm." ...
He cries, "I am a man of peace!"
She smiles; she says, "I am a woman of war" ... [122-3]
That bad things are done to you is bad enough; worse is the double-think that follows. The man insists -- often semi-sincerely, though he has some inkling of his motives because if you question them, he gets mad -- that (1) he didn't do anything, you must be hallucinating; (2) he did it but it's trivial and therefore you're irrational ("hysterical") to resent it or be hurt; (3) it's important but you're wrong to take it personally because he didn't mean it personally; (4) it's important and personal but you provoked it, i.e., it's your fault and not his. Worse still, he often insists on all of them at once. In this sort of ideologically mystified situation, clarity is crucial. Let us get several things clear: hurting people makes them angry, anger turns to hate when the anger is chronic and accompanied by helplessness, and although you can bully or shame people into not showing their anger, the only way to stop the anger is to stop the hurt. The cure for hate is power -- not power to hurt the hurter, but power to make the hurter stop.That was 1973, and it's still cutting-edge, as you can see in some of the comments (especially this one) on this 2010 interview with the editor of a book of essays on Russ's work. I've had enough debates in the past decade with well-meaning (I know they're well-meaning because they tell me so, quite insistently) males in sf / fantasy fandom to know that things haven't changed much in the genre over the past four decades. Anger is definitely out in the gay and feminist movements we now have, dominated as they are by their therapeutic / professional wings, but they were never really in, not that much.
It's a mistake to think that man-hating is a delicate self-indulgence; it's very unpleasant. ...
But back to Joanna Russ. She didn't write anything in her later years because she suffered from Chronic Fatigue Syndrome and arthritis. That was a loss, to her as much to her readers I'm sure, but the work she did manage to do is still with us, in used bookstores and libraries. Her short-story collections, especially the Alyx stories and The Zanzibar Cat, are probably the most accessible introduction to her fiction, and everybody should read How to Suppress Women's Writing. It's one reason I love books: even long after an author dies, even if I never met her in person, she can still speak to me on the page.
P.S. Nicola Griffith linked to this fine appreciation of Russ today.