Didactic, Poetic
Didactic
A lot of Woman on the Edge of Time is devoted to telling you stuff about the future, so you know how great the future is and can say, "Awesome, let's organize things like the future now. Pass the baby-birthing tubes, please."
Parts of this can read like a textbook or an instruction manual:
"Most of what children must learn, they learn by doing. Under five, fasure they need toys to learn coordination, dexterity, they practice tenderness on dolls." (7.80)
Except for the little bit of future language, that almost sounds like it's out of a child-rearing manual.
Poetic
However, Marge Piercy doesn't write child-rearing manuals. Instead, in her off-hours from writing novels, she writes poetry. And even when Woman on the Edge of Time seems matter-of-fact and dry, if you look a little closer you can see the poetic language peeping out to whack you with a metaphor.
She hated them, the bland bottleborn monsters of the future, born without pain, multicolored like a litter of puppies without the stigmata of race and sex. (5.60)
Read that out loud; that's some great alliteration on "bland bottleborn monsters." Or check out the phrase "She felt bewildered with space" (12.1); that's a lovely way of describing how Connie feels when she's free of the asylum.
There's some little spark of description like that on almost every page, hidden away between the suspense and the meanness and the crazy ideal future. Connie suffers, but she suffers in a sea of beautiful prose. Maybe it's all those lovely words in her head that let her get to Mattapoisett.