"Death Masks" is a pretty good entry into the Dresden Files series. However, one point simply MUST be deducted for the Return of Susan. Harry's lover is back - temporarily - and she's all around wonderful, even more so than previously. She's now superstrong, supersexy, supercapable, a member of a supersecret super-organisation, and what have you. This is getting very dull very fast, plus I simply can't take any more of her oh-so-rich lips and oh-so-sensual body - seriously, I had to start skipping those descriptions. There's no danger, no matter how deadly, which will stop Harry from noting how shaply her legs are. There's an especially bad bit late on where basically they have to spend the night at his apartment and he has to stop her from feeding on him. Now we know that Harry has a summoning circle capable of holding demons in his basement, but of course that wouldn't be as cinematic as his tying her up and then sleeping with her. Yeesh.
For those interested, the book also contains a very small helping of Thomas Raith. He's only in it for a couple of pages but those are about a million times more fun than all of Susan's combined.
Other than that, the plot is sound and interesting, with the usual couple of mistakes - at one point Harry keeps a magic shield going without his bracelet until it overloads and his bracelet WHICH HE DOESN'T HAVE burns him -, some interesting repeat performances and some interesting new characters, too.