I drove one last weekend and you can use the stick (push/pull) to change but I defaulted to using the steering wheel controls - although they were particularly more difficult to get used to than the M3's right=up, left=down paddles as mentioned earlier in the thread.  The default PDK steering wheel controls are the same on either side of the wheel - push from behind to change up, push from the front to change down - very unnatural to me versus the M3's DCT arrangement and I've hardly used sequential gearboxes before.