I had been warned that the Dresden Files series took a little while to warm up, and that's certainly proving to be true. The difference in quality between Summer Knight and Storm Front is quite noticeable. The story is much tighter, the writing is more straightforward, and the characters are more "in character." 
 I've noticed other differences, too. The "Noir" shtick has relaxed a bit, so Summer Knight relies more on its own atmosphere rather than simply borrowing conventions. The sexism is also much more subtle - Dresden is still powerless not to help a "damsel in distress" and women's appearance is still described in far more fetishistic terms that men's (when men's appearance is described at all), but the women are getting more agency as the series progresses. Murphy, in particular, is changing quite drastically. Though she's mostly just a convenient side-plot in this novel, her presence is no longer marked by her erratic behaviour. 
 The plot for Summer Knight returns to the fairies. After finding out about Dresden's fairy godmother in the last book, and his debt to her, we find out that the debt has been sold to the queen of the winter fairies. Worse yet, Dresden must complete a task for her if he's ever to get out of his obligation to her and save the wizards from the war he started with the vampire Red Court. Yeah, it's starting to get a little complicated. 
 The only complaint I have is one I nearly always have when dealing with the fae - there's an emphasis on how alien they are, and how incomprehensible their thinking from a human vantage point. And yet, for the purposes of solving a mystery involving them, and for the purposes of interacting with them, they are written in a way that makes their thinking seem perfectly rational and ordinary (albeit their concerns are shifted towards things and territories and matters that are more relevant to them). This leads to a disconnect between the way that they are described and the way that we see them behave. It's a minor quibble, but I do wish that Butcher would either spend less time going on and on about how alien they are, or spend a little more time actually making them so.