I agree with Onyx, this one was very much conceived as a portrait lens. It is the technological progression from the venerable 105/2.8. Just like the 135DC vs the 135/2.8. I believe Nikon wanted to create a lens that pleases both Leica (ultimate bokeh, very good sharpness) defectors and Nikon (ultimate sharness, so-so bokeh) fans by giving them a choice, and letting them decide which way the OOF parts of the image should look like by changing the degree of (over-)correcting spherical abberation.
I also believe that Nikon marketing muddied that idea with clumsy excuses like "control where the depth of field lies". This lens really lets you customise bokeh to your liking, DOF shifting is just a gimmick IMHO. This is hinted by Nikon's statement that the real effect of "Defocus Image Control" (sic!) cannot be judged in the view finder.
Seems like a perfect lens to experiment with in the digital age (instant turn-around).
Needless to say, I envy every owner of a DC Nikkor...
Cheers
Steffen.