I tried to watch the Dresden Files TV show since I'm a huge fan of the books...it's not good, to put it mildly. Even putting aside everything that's changed from the books (which could be a whole post in itself; aside from a few names and the general concept, they have nothing in common), it's just not a good show in general. There's almost no world-building, at least not in the first three episodes - it's just Harry fighting whatever monster is terrorizing Chicago that week. I remember a minor plot point in the first episode was that Dresden was having issues with his girlfriend, a plot point that doesn't come up later, nor is the girlfriend ever even mentioned in the following episodes. Oh, and of course, there's almost no magic in the first few episodes, it's mainly just monsters and Harry pulling a MacGuffin out of his ass to save the day (a "doom box" in the first episode, an ancient Egyptian tablet in the second). Maybe it gets better as the show goes on, but right now the best positive I can say about it is that the acting is alright, and I do like Paul Blackthorne as Dresden.
On the more positive side, I did start watching Arrow on a friend's recommendation, and it's much, much better. The first few episodes were a little rocky, but the acting is great, the characters are great, and I love that even though it's been sort of villain-of-the-week, every episode expands on what happened to Oliver on the island. I definitely recommend it if you're into superhero stuff, it's pretty solid.