Okay, first of all, if I had been able to give this 2.5 stars, I would have. It's a decent read, but I had some major issues with it. *SPOILERS ALERT* 
 - I never cared who was going to lead the Goblin Market, so that whole plotline seemed like a distraction for me throughout. 
 - I'm not sure I like the book being in Sin's POV. On one hand, Sarah Rees Brennan demonstrates her great ability to create characters, because I like Sin a LOT more at the end than I did going into the book. Yet, even with that consideration, there were so many times when it was felt she was too far distant from the action or didn't truly know the other characters well enough to describe the action in the best way for readers. 
 - Jamie's transformation. Sigh. I just flat-out didn't believe this one - that he would 1) be comfortable with knives, 2) betray Nick (even in a small way, when he really didn't mean it), 3)be as tough as he seemed in this one. I missed his scared and witty repartee, and it's completely gone in this book! 
 - Too much ideological angling. Sarah Rees Brennan did an awesome job in the first two books of this series of conveying characters with "alternative lifestyles," but sadly it felt forced in this one. I didn't like that she hinted Sin's race could be an issue for relationships, because I never felt it was to begin with, so I didn't like explicitly being told that. I also usually love what Sarah does with Jamie's relationships, but I just didn't get Seb in this one. It felt like the only reason he was in the plot was to fulfill Jamie's "happy ending." Also, the random reference to Matthias' two moms at the end felt totally staged - it wasn't really supported by the story. 
 - The solution to saving Alan? Put demons into "bad" magicians!? What happens when there are no more bad magicians and the demons still want bodies? I couldn't believe that was the best solution! 
 - Alan and Sin. They grew on me, I have to admit, but I still don't really like them as a couple. Maybe it's just that I didn't have enough time to see how Sin could really KNOW and UNDERSTAND Alan. Nick and Mae get three books to come together, and Alan and Sin are just kinda thrown together at the last minute. I guess I just wanted more here before I embrace them as a couple. :) 
 - WOULD SOMEONE PLEASE GO SAVE ALAN!!! I saved the worst for last. It drove me nuts that all the other characters scurry around worrying about stupid, mundane stuff like who's going to rule the Goblin Market and whether or not Seb really likes Jamie when Alan is POSSESSED!!! It took so many pages for them to help him! This was clearly the high point of the series, the big test of Nick's "feelings" that we'd all been waiting for, and it simply felt glossed over to me. In a different POV, I think this story arc and the brothers' emotions could have been heightened to levels of sheer awesomeness. 
 Not a bad book, but not quite what I was hoping for to wrap up the series. 
 Write Me A World