A lyrical, dreamlike, overwrought melodrama. By far its greatest success is in language. Youmans manages to use words and constructions of the period extensively and still sound smooth and natural, both in dialogue and in prose. It's a real triumph, the best of its kind I've seen. The language in general is excellent, consistently vivid and original, and the glossary at the end, especially the dialect parts, was wonderful. The descriptions of nature and of dressmaking, cooking, etc are very expressive, genuinely fascinating.
However, despite its consistent success in accuracy, the dialogue overall is poor, and just the first of the story's significant faults. It's not so much expository as just far too convenient, with characters repeating other's traits and pasts and plans ad nauseam. And it's much too flowery, giving the constant impression of planned and thought out speeches. If it were framed as a period memoir, since it's told in first person anyway, it could be more believable as such, but it isn't. The character work is very shallow. All but one of them are totally static and simplistic, and that one's development is "liking Charis to being manipulated into not liking Charis". The romance has an unusual aspect that I liked a lot, but other than that it's no good, and unfortunately it's one of the major parts of the book. The love interest has no meaningful faults whatsoever, has all virtues, and is totally devoted to Charis. This could also describe all the other protagonists. Charis herself makes a poor narrator, very caught up in herself, dull, repetitive, and annoying. Like all the protagonists, she's too faultless and flat to be effective in a novel of manners, and the rest of them continuously extol her virtues. Her victories over her purely malicious enemies are unpleasantly triumphalist, and she and her friends just happen to have currently-approved opinions. The plot is hung together by constant references to the deaths of Charis's family at the beginning, but it's really just a narrative of a few years of her life, though the most interesting ones.
Despite these issues, it's a reasonably entertaining story, and the language is truly beautiful. Low three stars.