I thought this book was OK but I gave it three stars since the rating system on this site skirts to higher numbers.
The world is standard fantasy stuff, consisting of a village, a mountain and a big city. The big city has an interesting structure of an archipelago of artificial islands. The author manages to bring color and atmosphere to the two islands where most of the story happens.
The social system is based on work division that's been featured in a lot of YA books since the success of Hunger Games. It's nothing to write home about. The author goes in depth about injustice of the system for about half of the book but then mostly ignores it in the second half in favour of action sequences.
The main character is a teenage girl who gets thrown out of her village and instead of whining about it to a hot grumpy guy, she takes initiative and goes on an adventure. She has some useful skills that she trades for help and knowledge required to survive. She's nice and friendly but doesn't take shit from anyone once she sees where the wind blows. There's not much place for growth but little by little she becomes experienced and does away with her insecurities. I think that makes her a good heroine for an action adventure book. The rest of the characters aren't very interesting. The mad sorcerer is disappointing, I think it's really high time for Master Elodin from Kingkiller Chronicles became the go-to copy-pasta for mad professor types. I suppose the sidekick guy being a normal cocky, upstart young assassin instead of some of more annoying YA character archetypes is a plus. And the evil mama was kind of a fun villain but I suppose that's not how most villains want to be percieved.
The writing style makes this book easy to read. Creeping around at night is a bit scary, child gang warfare makes you worry about our headstrong heroine for a little bit, fight scenes make you worry about her poor enemies. There's some juicy parts in here, nothing special, but it's a bit refreshing because the girl takes some initiative. Uhhhm, and I'll just pretend she's over 18, don't know how that flied past proof readers.
The magic isn't elaborately described, there's the normal kind and Kara's type, which triumphs over that other one.
All in all, I recommend it to people who want an easy to read action adventure with a teenager in the main role. If you want extensive worldbuilding, complex magic system, a lot of interesting characters or thoughtful social commentary, look elsewhere.