It took me a full year to read this. That's not a good sign. 
 Sometimes I start a book, then stop for a while because I become distracted by something else, then I'll go back to it a fair while later and enjoy it. That was not the case here. Glass Sword drove me batty. I really disliked it. Red Queen wasn't great, but it wasn't bad either. This second book took a nosedive, though; it really didn't work for me. 
 Mare is a horrible character. She's selfish and her ego is so inflated that she's convinced the whole world revolves around her. One example of something that really irritated me: she goes on about how the silvers are bad because of their powers, yet she looks down on her own friend multiple times simply because he's not a new blood and doesn't have any powers of his own. 
 She's also caught up on Maven, and I really do not understand why. He showed his true colours in the previous book, you'd have thought him trying to kill her would burn away any lingering feelings. Especially since he's also trying to kill anyone like her before she can get to them - and sometimes succeeding in this endeavour. He's a psychopath, not a romantic interest. 
 The story seemed like a fantasy in the first book, set on an Earth-like planet, but now it's looking more like it's going to be sci-fi set in the distant future. Yet there's nothing put in place to help explain how society could go from ours to theirs. 
 The whole story is boring. It's supposed to be action-packed, but even the action is boring. The author has this really annoying habit of not bothering to write the important bits of a scene, and just filling the reader in on events afterwards. E.g. (view spoiler)[when Mare kills the Queen mother, we don't actually see it happen. We're just told about it afterwards. (hide spoiler)] 
 I wanted to like this book. I even pre-ordered it, despite thinking Red Queen was only a 3 star read. But it just really did not work for me. 
 I don't know yet whether or not I'm done with this series, or whether I'll put myself through the pain of the next two books, just as a form of completionism. Time will tell.