I have small framed prints of the summer and winter queens, somewhere in a box! I read this in my teens and loved it, not least because it was adult science fiction with female characters who weren't written by Anne McCaffery. I am very fond of World's End, which is the short interstitial novel between the two and is basically BZ Gundhalinu doing Heart of Darkness in space, but it has been a while and I'm not sure how well it's aged. I do have a lot of fondness for this and also her Cat/Psion series.