White isnt too bad to keep looking nice. Sure it gets dirty quick but not the same as black. It becomes a more uniform grey the dirtier it gets. As for stone chips, they do show up but the primer is light grey so they are not as noticable as some of the other colors available.
I didnt want white when I bought the car, now, I'd only consider black as an alternate to white. The white is really nice, plus I only saw 1 other WRX in white in the 2 years I owned the car.