I wanted to like it more than I did, and I liked it more than I wanted to. It's contradictory, but that's just how this book is. One way, the book is a beautiful story of choices. Another, it's a grim story of choices. Patricia lives two contradictory lives that diverge greatly from a single choice. 
 I wanted to like it more than I did. Jo Walton has a talent for words, and the book was highly praised over on Tor, where I first heard about it. Patricia's lives are summarized so quickly over the course of 300-some pages in order to cram in all the major details, that I didn't even know that both lives were alternate histories at first. Years fly by in mere paragraphs, and world events are mentioned only in the background, so it's easy to miss things. The ending is also simplistic. (view spoiler)[Patricia seems to have the final choice of which world should be real, the violent one where she lived happily, or the peaceful one where she lived unhappily. It seems to imply both that the choice is obvious, and that both choices are real (all the children are real). The choice is too obviously a trade-off between her happiness versus the world's. Is the choice not to choose a valid choice? (hide spoiler)] 
 I liked it more than I wanted to. The prose, while mostly summarizing, is evocative, and the major characters, especially the children, are all distinct and memorable. The divergent results of the one choice are heartbreakingly different on both a personal and global level. But I really didn't like how gratuitous the alternative lifestyles were, and the implication that the regular marriage was doomed and mostly sexless while the alternative relationship was automatically happy. It felt like the alternative lifestyles were being crammed into the story in a very post-modern way without exploring the consequences. (view spoiler)[The threesome was totally unnecessary, and would Patricia really have been okay with her partner using the same man to sire children? Weren't there sperm banks in that version of the world? Nobody would officially do artificial insemination for them, but even so, surely they could get sperm from a guy without actually having to have sex with him. (hide spoiler)] 
 Bottom line, it's a good concept, but the execution was seriously flawed in my opinion.