[I'm trying not to be spoilery, but maybe skip this review if you haven't read book 1 yet.] 
 Dark YA that is very close to being adult UF. 
 It's a middle book - middle books aren't really my favorite (I know they have to happen to bridge events from book 1 to 3, but they always feel so unfinished). You get some answers, but that just leads to more questions. I still like book 1 best so far. That isn't to say I dislike it - this is a good continuation of the series and many necessary things happen. 
 I like the world, the characters, the magic (we get to see more of the necro and witch world here). Loved Peter in this one, wanted to punch Simon (and alternately punch or hug Beck), shake and hug Riley (how much does this kid have to take!), and Ori, well, I'm just not going there yet. And the end is a non-stop ride of "Holy crap! What just happened?" 
 I got how Riley wanted to have things to do, was looking for anything and anyone who could be a distraction. If she stops moving, she has to think about everything that's happened and the upcoming Armageddon. The book starts the day after all of the events in book 1, so she's had zero time to adjust to anything. 
 I was reminded a lot of the episode of Buffy where she and Angel sleep together then he turns evil. Consequences. Everything has consequences. And everything is a grey area too. 
 I do like that balance was a constant theme here. We get to see more of the Divine, but that doesn't necessarily mean what you think it does. I do like the direction this is going, even though it is also gut-wrenching. Will be interesting to see how things come together in book 3.