*edit* Wow, second time double posting, both times on a Mac..... Down with Safari!
Anyway, I would have to disagree with the people who say that the analog stick is better for moving. In my case, I can move my fingers with WSAD the same way I could rotate the left analog stick while I'm looking around. Also, With the keyboard/mouse controls, I don't have to sacrifice any movement or aiming when I want to do something (like reload). Take the controller, you have to sacrifice one of your thumbs from the left or right analog stick to do things like change weapons, reload, jump, ect.
When it comes to movement and looking around, Portal is another great example. The game was a nightmare with the controller on the PS3, but controlling it with a keyboard and mouse felt much more natural and I'm suddenly able to use the portal gun to it's full effect.
