Let me add that downshifting this way is not subject to the 6 sec mandatory manual interval you get if you downshift with the paddles....
Also, if driving in auto mode and you want a quick down shift to the best lower gear, just a quick prod of the throttle and the car auto downshifts immediately. So simple, so useful.
This has its pros and cons. If you downshift to floor it (for passing another car, or because you remembered you need some coffee) it is great, you punch briefly the pedal about an inch and you get one downshift, you punch it two inches and you get two or more gears down (you need some experience on how much to punch, NOT pedal to the metal). Then you can feed it gas as you see appropriate, and the PDK will do its job as it sees appropriate.
The con is when you downshift by punching 2 inches for braking. It is very counterintuitive and man, oh man, it can scare civilians, women and children. But, as I said in the beginning, it is not subject to the 6 sec manual hold. Where this 6 sec can surprise you (if not turn around and bite you) is if you downshift with the paddle and come to a stop, say at a light, before the 6 sec are up, it will stay in manual. When you start in 1st, it will be in manual and surprise you by not up shifting to 2nd, for a while.