Your criticisms of the first book are mostly valid, though it does get better throughout the book.

It offers a hint at better things to come. Dresden himself is interesting enough, with enough history and internal conflict to keep a person interested. The magic and some of the secondary characters are fun.

Butcher uses the positives of the first novel, a developing capacity as a writer, and the serial nature of the series, to really build something that is captivating and entertaining. It isn't literature, but is pretty good popcorn entertainment, with a good deal of darkness and internal conflict to go with the series long character development of Harry and those who rotate in and out of his life.

I wasn't really hooked until the 3rd book.