This is set in the same universe as Samatar's "A Stranger in Olondria." I have not read that one. It's possible I might have gotten more out of this if I had, however, there are plenty of reviews saying this one works as a standalone, so I'm reviewing it as a standalone.
Premise: Olondria is an on-again, off-again empire, built from three closely-related peoples--the Laths, Nain, and Kestenya. The Laths consider themselves favored of the gods (unfortunately, one of the side effects of divine intervention is creepy vampires), and try to conquer/ally with the other two. Their default line of succession is from the king to his sister's son, and only to the king's son if he has no nephews of his own, which allows for neat political dynamics (Arthuriana vibes, nice!) The feredhai are nomadic people from Kestenya, who resent the concept of land ownership and other border controls imposed by authorities with written rules. A couple generations ago, one of the rebellious Kestenya leaders grew too horrified at the Laths' slaughter of civilians, and betrayed his allies to seek a peaceful resolution to the war. In return, he was granted the Lath princess' hand in marriage, and the new royal family is a blend of Laths, Kestenya, and Nain families, with a pair of sisters marrying a pair of brothers to create a double cousin dynamic. Meanwhile, a new ascetic religious movement, the "Cult of the Stone," has emerged and gained influence among the ruling elite; the devotees try to translate inscriptions off an ancient stone, and put them together to build a scripture focused around the value of reading and writing while avoiding sensual pleasures or wealth, while ignoring any texts that don't seem to fit the austere tone.
Prince Dasya is the heir to the throne; Siski and Tavis (aka Tav) are his cousins. Tav dresses up in boys' clothes to join the army and fight against the Brogyars, but becomes disillusioned with war and empire, and later falls in love with Seren, a feredhai poet. Tav and Dasya plot to start a revolution to bring down the Olondrian empire and the Cult of the Stone and win independence for Kestenya. Results are mixed.
What I just summarized is much more straightforward and linear than the way the book is actually presented. Each section is highly nonlinear in a kind of free association way: one character smells or sees or hears something that evokes of her past, and it abruptly jumps around between timeframes. There's a lot of descriptive prose, but to me, it felt more like "throwing a lot of words at the wall and seeing what sticks." Sentence fragments. Like this. No verbs. Or run-on sentences that talk about this war and then the war two generations ago and then the war described by In-Universe Scholar in her epic poem, "War Is Hell," and then a vague reminder there are vampires but that's probably not very important. I like in-universe documentation when it's done well, but here it didn't feel like it was adding much, just a vibe-based barrage of names.
I'm semi-randomly going to quote a representative example from each of the four sections:
Tav says that she's not really good with words, she's just a soldier, but I personally found all of the sections to be more concerned with trying to convey a sense of "poetic" prose than giving distinct character voices.
The closest "comparison" book I would think of for this one is Tigana, by Guy Gavriel Kay, which has vivid prose and also deals with the pros and cons of trying to overthrow an empire in the name of older nations, outsider POVs on the prince who's trying to take back his homeland, and evocative descriptions of in-universe religion and lore. Tigana, however, has more of a sense of humor, and the prose--while rich--is more straightforward both on a sentence level and overall chronological level.
(On the other hand, "Tigana" also has a creepy but pointless sibling incest plot; "Winged Histories" has a complicated cousin incest plot that actually goes somewhere. So advantage to "Winged Histories" on this specific comparison.)
In describing feredhai music, Seren notes that "You will have noticed that all the great songs are sad." Nobody in this book spends a lot of time being happy, and while I understand that war is hell, when it's just unrelenting misery it makes it difficult to care! Tav's sympathetic backstory is "my terrible aunt threw my book of women soldiers in the fire." Tialon makes up a trauma-porn backstory for her father, then admits it's a total fabrication because he never told her anything about himself. Seren loves Tav...except that her people are warriors who die while Tav's people are spoiled sellouts, because empire is terrible and destroys everything it touches. Maybe we're supposed to believe they can change the narrative, but I'm not confident! And Siski has nothing else to live for, so she might as well die with her cousin, except maybe she's not actually going to die, maybe it's a new beginning. Maybe. Imagine. Perhaps. Ambiguity. All vibes. The loose ends that "Tigana" left unresolved were frustrating; "Winged Histories"' weren't, because I didn't really care in the first place.
Bingo: Hidden Gem, Down with the System, Book In Parts, was a previous Readalong, Author of Color, Small Press, LGBTQIA protagonist.