I just finished reading Revenant Gun by Yoon-Ha Lee: it's the end of the Machineries of Empire trilogy. It's a dark, complex space opera setting -- the basic premise is that the physics and technological possibilities of this universe are determined by the calendar the empire observes: not just a matter of how long days or weeks are, but also a matter of holidays and observances, which involve gruesome executions of 'heretics' (who have challenged or failed to follow the Calendar.) The math of the Calendar and the technologies (indistinguishable from magic) that it enables undergird this entire interstellar empire, governed by an alliance of factions with their own habits, culture and priorities jostling for position. The plot is twisty in the extreme, but I feel like it's the characters and the world I primarily come back for. The hard choices they make, the ways they audaciously begin to imagine a better world from deep inside the workings of this one. Very satisfying.
I really like these books, even though the second book pulled a plot maneuver I found highly suspect and convenient, toward the end. (You can tell I forgave it, because as soon as I finished listening to Book 2, I restarted Book 1, then listened to Book 2 again right after. And I do not usually reread things that quickly!) Book 3 redeemed that convenient maneuver quite a bit by showing complexities that resulted from its 'too easy, too simple' resolution. One of the new POV characters was very different and loads of fun, too!
Obviously, you shouldn't read Revenant Gun if you haven't read Ninefox Gambit and Raven Stratagem, but I really enjoy this series and recommend it! My reader warnings would be: It's somewhat gruesome in bits, and some of the characters have sexual mores that are weird and offputting even for the society they live in but they're sort of part of the great tapestry of the weirdness that is the setting. (For instance, there's a POV character in Book 2 who despite being asexual is Friends With Benefits with his sibling. Who has been surgically altered to look just like him as an anti-assassination decoy. So many layers of weird on top of that ick.) There is no graphic sexual violence, but coercion is a major ethical theme of the books and is sometimes sexual -- there's a lot of plot around the impossibility of free consent across lines of rank and obedience. (The military's obedience is involuntary, conditioned and calendrically/magically enforced, so members of the military faction are not allowed to fraternize, on pain of death.)
The books are dark, but they're also mind-blowing, with lots of good Sense of Wonder moments. They transport you instantly to this strange, high-stakes world of intrigue, space battles, lies and grand drama. Immersive and exciting.