I must be the only who didn't love this book to death...
Cold Days was quite good and I liked learning more about the Outsiders, Winter/Summer's roles, etc. But that being said, after the "oomph" of the last two books, the story felt way too much like a typical Dresden plot.
Also, I felt that all of Harry's old friends got over him being alive again way too easily. Granted, it had been several months since he "died", but almost everyone accepted him being back without batting an eye. Especially after Ghost Story. They may have had doubts about his personality or loyalty, but they didn't seem to have any problem with him coming back from the dead. I'm getting a little of the recent trend in fantasy to treat death like it's no big deal.
I enjoyed the book, but it felt like Butcher was trying too hard to get things back to normal.