This is kind of two books, of which the first half was fun but frustrating, and the second half generally better.
In the first half, we're introduced to two main characters in separate worlds. Nahri the orphan who has some strange powers and turns out to be at least partly Djinn-descended, possibly the last survivor of an important dynasty. And Ali a prince in a brutal dynasty that murdered most of Nahri's ancestors, and who is determined to do something about the cruelty. Nahri has to flee her old life for Ali's city. The writing is clunky at times, Ali's a little too good, and it's too obvious that Nahri's flight will succeed, so the epic battle with every kind of magical demon feels more farcical than exciting. But the book's great strength is that this "conclusion" is only halfway through it.
What made the second half work better for me is that Nahri's arrival is such a complicating event in everyone's life, most definitely including her own. Ali ends up thoroughly compromised in ways that make him a much more believable character, and the interwoven strands of everyone lying to and scheming around each other get much more interesting. And I think Chakraborty just took a while to hit her stride as a writer, which makes sense given that this was her first book and not originally written with publication in mind.
At the end I was still a little frustrated. The hooks for the sequel are slightly too obvious and undermine the completeness of this (already long) book, and there are a few too many deus ex machina. But considering how much better the book got as it went along, I am excited about the sequel.
