There are more than enough reviews of this book already, so I'm not going to say much. Really for me is boils down to this: average book is average. Unextraordinary, plain, orphan girl discovers she is The Chosen One, and begins her journey to save the world. On the way she ends up in a magic school where she had trouble fitting in, and meets Mysterious Bad Boy, while pining for the Good Boy from her childhood. The story just sort of clips along without ever bringing any real surprises or revelations. It's perfectly fine, but ultimately forgettable.
Here's the thing: I read Six of Crows first, and I loved it. In fact, I loved it enough that I'm willing to give this series the benefit of the doubt and stick with it. (Had I started with this book I doubt I'd bother.) I know Bardugo can write (though she's much better at 3rd person POV than 1st, which is the POV she uses in this trilogy). All in all the book wasn't bad, just uninspired. My advice? If you're diving into the Grisha world for the first time skip ahead to her duology (Six of Crows & Crooked Kingdom) - the writing is better, the plot more complex, the characters more fleshed out and interesting, and the story more surprising and original. As for me I'm going to tear through the rest of the trilogy just so I can hang out in Grisha land a little bit longer.