"Woman on the Edge of Time" is an excellent read. Marge Piercy did an outstanding job with this book; it was written in the 1970s, and does not appear dated. The themes are universal; how does anyone live with hopelessness and despair when their back is against the wall? And, can love win out over hate?
I'm not doing Ms. Piercy's book justice; there aren't any words to describe how profoundly meaningful this book is about those universal themes.
As for the plot, Connie Ramos is in her mid-30s, has had mental problems in the past, had her daughter taken away from her due to Connie's having gone through a rough patch in her life (her partner died and no one cared about it but her; she acted out and did drugs, which caused her to mistreat her daughter). No one seems to care about Connie; she's lost her looks, she has no money, and even her favorite people mostly just ignore her.
What astonishes me about Connie and her plight is that she is intelligent. She had some college, yet no one that deals with her ever considers her intelligent _or_ educated. And that's stupid; really, why didn't her welfare caseworker say, "Oh, Connie, you have a year or two of college. Would you like to be re-trained?" In real life, this might have happened.
However, this _is_ a fable; that can be overlooked. Besides, the social services in the 1970s in New York were terrible; they rivaled the situation that New York faces today after the terrorist attacks. There are too many people; it's very easy to get lost in the cracks. So this isn't a plot hole at all; it's a statement about how good people often get downtrodden through no fault of their own.
Anyway, Connie isn't listened to about anything, so when her niece comes in and begs for sanctuary, Connie probably should have sent her away. But Connie's kindhearted; she doesn't. That kind act gets Connie beaten and thrown into a mental hospital; while trying to defend her niece (who then promptly goes back with her abusive partner, a pimp), she broke the pimp's nose. He gets Connie committed, as she has a previous history of mental problems.
From there, things go from bad to worse; Connie is forced to participate in experimental treatments in order to ever go home, because no one really wants her anywhere. The state doesn't care, her family doesn't care, and the one man who loved her is dead. (Her daughter is either in foster care or has been adopted out.)
She makes contact with the future and manages to use those brief glimpses to continue to hope and fight her situation. She pretends to acquiesce, but is in actuality looking for a way out -- if it'll only present itself.
The subplot about the evil future, to me at least, is a metaphor. There are always choices. Even the best choice can lead to ill; you can only minimize the consequences.
At any rate, Connie's situation is appalling. Her only true friends are those in her head -- those from the future. Yet she continues to care about the present, despite having almost nobody or nothing care about her except as an object.
Anyway, Ms. Piercy does not normally write s/f. Her world-building skills, compared to contemporary s/f authors, are not what most s/f readers look for. There aren't elaborate scenes sketched; there aren't large amounts of technology lavishly explained.
I feel that is irrelevant. Ms. Piercy has enough detail of the future, both good and bad, to explain what's going on, and that's enough for me. I liked her additional words (per for a personal pronoun, rather than he or she, for example), and I enjoyed her descriptions of how things were done in the various encampments/towns. And really, this is a highly personal novel; it's psychological, and can be read on many levels. That level of minutiae would only distract, not add.
Those who want more conventionality need to look elsewhere.
As it stands, I think "Woman on the Edge of Time" is about love, and how it can conquer anything. Granted, the love I'm talking about isn't about love for another -- or even self-love, although Connie does have those (especially for her daughter, who was taken away from her during her dark period). It's about love for humanity, which is what makes it so unique in science fiction. Ms. Piercy tackled a huge theme, and made it work.
There aren't anywhere near enough stars to give this work, so I'll just say five stars plus, with the highest recommendation possible.