I finished it last night and I loved it. I was a little wary going in on how this one would turn out but Butcher beat my low expectations over the head and pulled it off magnificently.
I loved Harry's "killer" reveal. I felt like it added more depth not just to Ghost Story, but to Changes as well. In Changes we finally see Harry go over the edge, crossing the line into darkness to protect the people he loves, and in Ghost Story we learn that not only was he willing to cross that line, he was willing to die for it. Let's just say it got awfully dusty in my house when I was reading that. And when he finally see's his daughter. And when we finally see Thomas. Jeez. As a side note, I don't think the Winter Knight thing will last more than a book or two, so I don't expect it to effect the overall series much, much like Lash when she was infesting Dresden's brain.
As far as the book as a whole and Butcher's writing, I think the seams have been showing in the Dresden Files formula for a long time, and for a while (specifically around Turn Coat) it bothered me some, but I seem to have gotten past that and just accepted the books for what they are. They characters are still powerful and moving like almost nothing else I've read, though that's partially because there are so many books the characters have been allowed to develop to extraordinary depths.