I leave this one with fairly mixed feelings. It is eminently clear to me why it's a staple of the genre, and in terms of world-building and set-up it's glorious - fascinating and strange but also in parts familiar. Also a good trait in sci fi: considering how differences in setting, advancement and world-building would affect social injustice - or not.

One of my longstanding sci fi gripes (and also to a lesser extent fantasy gripes) is that the world-building and exposition come at the expense of characters and relationships. I think that hold true here, at least to a certain extent. Arienrhode, Jerusha, Ghundalinu, even Tor I found reasonably well-developed and compelling, but Moon and Sparks fell kind of flat for me. Most particularly, the love story I found deeply forced towards the end, and, from today's perspective, more than a little problematic. I also had trouble reading Arienrhode as an antagonist; certainly there was something of selfishness and callousness in a lot of her actions, but I still felt like she was working with faulty information and doing what she thought was right.

On the note of exposition: this was actually really weird to me, because the exposition comes right at the beginning where you'd think it belongs - which is a thing I haven't seen in most SF/F written after 2000, I dunno, I guess it's a passé way of doing things and we've all tooted the stupid "show don't tell" horn too much? This book definitely proves that you can do exposition well, and that it's not a question of showing or telling but of when and how much. And also that exposition is a good way to fool your readers into thinking that they know what's going on (although it would have been cool if the "winter barbarian" dudes had been at all relevant before they took over the plot).