I got used to the arrow keys when I was a kid. Later on, I got accustomed to WASD. I do think for things like first-person shooters, WASD plus a mouse is the only way to go. As some others pointed out, WASD lets you also hit E, Q, Tab, Left Shift, and Left Ctrl, without missing a beat. Gives my pinky a good workout.
That said, I also like games that I can control mostly with the numeric keypad (like the Civ games.)