paris1 is correct - heat was applied to ensure the paint remained flexible throughout the repair. The repair is smooth to the touch, but he explained that the slight discoloration is a result of the metal flexing as he brought the dent up and evened it back out. Again, it isn't 100% perfect and those of us who are particular about our cars will see it; someone walking by they car they are likely never to notice the subtle wave. He also polished and waxed the door, which makes it hardly noticeable. That said, I tend to think there is a bit of "muscle memory" - I know where the damage was and will always see it in my mind. I asked a colleague to point out where the dent was (didn't see it before the repair) and she was unable to tell the difference.
W/re: to cost and value for the service provided, I had three opinions on the dent before going with the more expensive option - the second PDR guy didn't instill confidence and wanted to drill a hole (um...no) and the third was from the collision shop I trust who a) recommended I pursue PDR before conventional repair, and b) took a look at the finished product, agreeing that it was as good as I could have hoped for given the depth of the dent. Net-net, I am happy and the repair is livable. Moreover, I have two good relationships now with reliable and trusted PDR and collision shops. I'll chalk it up to a win.