It was very odd to see Ali and Cole's relationship from an outsiders' POV. We get both Frosty and Milla's POV in this one and Ali and Cole aren't a huge part (they've got zombies to slay, after all), it is still really odd to see them from eyes other then each others.
I spent about have of this one unsure as to what was going on. Yeah it's a romance but Frosty with anyone but Kat just seemed wrong. It's hard to dislike Milla, even though I really wanted to. She is the one that betrayed Ali and their group to Anima, which got Kat killed.
The ending seemed a little too perfect. Everything works out and they even get an epoliuge about how perfect their lives are ten years after the start of the first book. It was nice to see Ali and Cole, and Frosty and Milla get happy endings but it was also a little too perfect.