The novels have been made, by Sci Fi Network, into a TV series. The TV series is, as is usually the case, inferior to the books. I've seen a lot of elements from the first two novels get spread across several episodes, breaking up coherent stories and using them as elements covering several other, shorter, "solved-in-forty-minutes" stories. But the TV series was good enough to keep me watching--at least until Battlestar Galactica turned into re-runs.
The books, however, are really good, at least as far as the ending of the second one.
Butcher has generated a cohesive framework of rules to contain his stories: magic is governed by laws and regulations which it will always follow, so there won't be any sudden, "But wait! I'll just wave my magic wand!" like Harry Potter or Star Trek. In fact, at the climax of the second book, Harry Dresden faces the book's primary antagonist almost totally drained of his ability to use magic.
The world Butcher has created is complex and lively, and there is a complex back story surrounding Dresden and his past. It's good stuff; so I heartily recommend that you go find the books and read them.