Very well-written, of course, but not the kind of book that inspires passionate advocacy -- or at least, not from me. I figured out the "twist" about 2/3 of the way through, but maybe you're supposed to. I don't know. The hint that tipped me off was pretty heavy-handed, but then the narrator continued to obscure and be coy, so I thought maybe I wasn't supposed to know. Whatever. It's not an O. Henry story -- there's a lot more to it than "twist."
The good: the language itself, the poetic turns of phrase, the stark insights.
The bad: the narrator's passivity amounts to complicity in the events she describes, which is all to be expected, and thematically resonant, and in line with the historical situation of women during the years the story takes place, etc., etc., but also means that it's difficult to like this woman enough to want to spend time with her at all, especially given the length of the book. She's pretty repugnant when you really look at her.