I don't know why I got away from this book like I did. It shouldn't take that long to read, and it's very, very good.
I love that the main characters in the book are strong women. I love that the world building is fully fleshed out. I love that it's a coming-of-age story that's not weak. I just kinda loved it all.
The story takes place on Tiamat (also, yeah, loving Vinge's use of names), which is a planet in the "Hegemony", that due to an astronomical fluke is "available" to the Hegemony for 150 of every 300 years.
When the Hegemony has access to Tiamat, the techno-forward, environment destorying "Winters" rule the planet (complete with it's Winter Queen) and during the inaccessible time, the primitive nature worshiping "Summers" rule.
This story takes place at the time of transition. The Winter Queen will do whatever it takes to keep her power, the Hegemony will do what it needs to to make sure that the transition happens (for reasons that are revealed, brilliantly, in the book). Arienrhod is the titular Snow Queen, a hard and scheming woman, who is not one dimension (for a refreshing change). Moon, the second of three main characters, is a product of Arienrhod's scheming, she is a Summer, who has the calling to become a sibyl. Thanks to her calling, she must end her relationship with her cousin, and their estrangement begins her journey that takes her off-world and then to the heart of the Hegemonic city. Jerusha PalaThion is a female "blue", basically the Hegemonic law enforcement. She struggles, dealing with the discrimination dealt to her from the men of her department, as she tries to unravel whatever it is that Arienrhod is up to (and she's pretty sure she's up to something). She's probably my favorite character in the book (right after Arienrhod).
I've seen numerous comparisons to other big works of sci-fi (most notably Dune, and to be honest, I think there is some truth to some of the comparisons). And while this does use some major themes/trops, it's also refreshing with it's strong female component.
Vinge's prose is also fantastic, and her world building is absolutely complete. The scraps of science and the reasoning behind motives is interesting and fascinating. Is it the most original thing ever? Probably not, but it's easily one of the best books I've ever read. As soon as it's available on kindle, I'll own it.