In the previous 13 Dresden Files books, the events were enjoyable, but they seemed disparate. There were epic conflicts involving faeries, necromancers, vampires, werewolves, crime lords, angels, demons, gods, wizards councils, evil islands, random individuals, and Harry Dresden, but there wasn't a sense that those were all connected. There were also a couple of things that Butcher had been foreshadowing for many books. With a couple of exceptions, "Cold Days" brings it all together.