Ghost Story is the 13th Harry Dresden novel, and it shows a striking self-awareness. Up until now, it's been easy to see Harry as a sort of Gary Stu, fighting his way through a lot of bad guys and walloping them with his more-impressive fire-power. But here, Harry confronts the idea that maybe discretion would have been the better course -- he's ended up causing a lot of problems, even as defeats the bad guys. We can see that Harry's hot-headedness has caused a chain of events starting way back (to book 3 or 4, I think), leading to the war against the Red Court, the death of his friends, the crippling of Michael, and so on.
Having said all that, the emphasis on the book is not on soul-searching, it's still on action. So it'll be interesting to see if Butcher has Harry turn over a new more restrained leaf, or whether book 14 goes back to business as usual.