This is a really good effort at a middle book in a trilogy. It bridges well the gap between building the characters in the first and the big climax in the third. This is the classic 'I'm trying to get out but they keep dragging me back in' part of the storyline, and it's been done in a sympathetic and believable way.
There's always a risk when the action and movement is being ramped-up that characterisation will be lost. The author sometimes teeters on the edge of this, but thankfully never quite tips over. The main characters you've grown to like from the first book actually find a deeper engagement with the reader, drawing you further into the story. The exception for me is Elene who I feel never really gets going as a character - a bit wishy-washy. To put it positively, the author has identified what works and is sticking with it.
Once he's back 'in' Kylar develops well in his power as the Night Angel, but always has the human frailties that give vulnerability where it's needed. The introduction of a broader geography gives him greater scope as a character but also places him in a bigger and more dangerous world. As his power grows, then so does the threat.
It's a big challenge to keep a storyline together when characters spread out across a world, but the author gives it a really good effort. None of them lose the big-picture but all of them also overcome their own back-story to give them greater depth. Whether they're all necessary to the story is another question, but they certainly don't detract.
Overall the book delivers excellently on the promise developed by the first one. If you like Kylar, Durzo, Logan, and Momma K, then don't delay in getting this. It gets stuck on four stars as it's not epic quality, but it's definitely a very very good first effort.