Fran Wilde writes pretty sentences, and ties them together to make you care about the characters and the world intensely.
The worldbuilding in this is glorious. Spires of bone that form a city above the clouds, sewn wings for flying and bridges between spires, rules and laws, the struggle between speaking and silence when it matters most, and the importance of screaming once in a while for good reason. Thematics of loyalty, love, balancing self and collective, and above all, perseverance and understanding when and how to sacrifice, and understanding how your own history influences those choices, permeate the book.
Kirit, the protagonist, is fully rounded: physically strong through long training, intelligent but not always prudent, incredibly resilient when everything but the kitchen sink gets thrown at her. She wants to fly, and she wants to help her city. She saves herself, and those around her, again and again.
[I can see why there has been confusion as to whether this book is YA or not; the main plot is basically a coming of age story, but it’s not particularly any more YA than any other secondary world fantasy that features a younger protagonist (say a farm boy) coming into their own (say, becoming a king).]
Full Disclosure: Fran is a friend who has been published in Uncanny, and who will be trapped for a whole weekend with me AGAIN in the Poconos for Uncanny Cabin II.