The problem with PDR is you have pretty much take the door apart to get behind the dent. The guys that do it hopefully know your model well and use care when getting in there to do the work....those plastic parts holding the door together can break when disconnecting everything....especially if the job is rushed.
The tools involved are often just rods of varying widths and lengths bent to get to the dent...but there are a lot of other tools that can be used.
I'm interested in this myself because I have about 4-5 door dings on the driver's side of my car. It's mainly from jerks out there and the thin sheet metal they put on cars these days. I'm going to hold off, but may try to get them touched up one of these days or spend a day and try to do it myself.