I am a huge fan of Leigh Bardugo. While her Grisha series ultimately had a few bumps in the road for me, for the most part I really liked it. I loved the unique aspects of her world building, and the vaguely Imperial Russia feel of her universe.
Six of Crows is set in the Grisha-verse, but not in Ravka (her answer to Russia). It is set in Ketterdam, which is very obviously based upon Amsterdam, with it's trade in the vices, including prostitution, and it's focus on commerce. This was one of my most anticipated books of the year, and, so far, it is not disappointing me. I am very much enjoying the characters, and the heist aspects of the story are fun. There is a sea-faring vibe that is very entertaining.
I can't pick a favorite character right now - maybe by the end I will, but for right now, I like them all. Each character is complex, with twists and turns and motivations that aren't quite clear.