I came late to the Dresden Files. As in, fall of 2011 late (12 books in), so this was the first in the series I actually had to wait for. 
 It was worth it! 
 *Beware - Spoilers Follow* 
 Boy, was it ever. Fans of the series will know the previous book tied up a lot of the questions about Harry's "death" at the close of Changes (#12), but Ghost Story (#13) ended with all of Harry's friends still thinking he was dead. So, I was really looking forward to the "Hey, guys, by the way, I'm still alive. Sorry I put you through hell." scenes in Cold Days. 
 Butcher doesn't disappoint. We get to see lots of great reunions, including with Harry's brother Thomas (My favorite of the bunch!), his apprentice Molly and, of course, with Karrin Murphy. I would have bet money going in that Murphy would punch Harry over the whole situation, but I like the way Butcher brings them together again even better. He shows us a new side to the characters' vulnerabilities while keeping their classic banter intact. 
 The other slight concern I had going into this book was the overall bad guy landscape. Butcher had thrown the author's equivalent of a nuclear bomb at it in Changes, and Ghost Story seemed poised to go in an entirely new direction. I wasn't quite ready to say bye to all the favorite old villains, and I'm glad to see several of them return here. Top of which was Mab, the Queen of Air and Darkness herself. 
 I've always thought Mab was a fascinating character, especially in the Dresden Files, but holy cow, I love how Butcher brings it to a whole new level in this book. He simultaneously makes her colder, more manipulative, and yet amazingly more human all at the same time! In the world of scheming faeries, I must say...I was on Mab's side the whole time. It was endearing and heartbreaking to see her "motherly" wisdom at the end. But I wouldn't have wanted it any other way. 
 Other things I loved about this book: 
 - The set up of the massive warfront against the Outsiders. This one was great for a couple reasons: 1) It means Harry has a legit reason to maintain a balance with the world of Faerie and, let's face it, you know that's gonna lead to all kinds of cool plot threads down the road, 2) We get a glimpse at the Gatekeeper's role in battle. 
 - Mac finally opens up...a little. Like three words. Still, I'm really intrigued to see where this one goes. 
 - Harry and Murph. 'Nuff said.