Aside from interface issues (which depend quite a bit on your style of shooting), I think the biggest drawback of the DS is the lack of a hand grip. One advantage is that the grip can hold extra batteries. Another is that you get a vertical grip with shutter release, which is very nice if you like that format. It also gives the camera some weight. I really like little cameras and will always take the DS as a walking around camera, especially with shorter lenses. For longer lenses or whenever I want a more stable platform, the heavier D/grip combo will just absorb more shake. I will admit, however, that the DS on good monopod is particularly fine walking stick ;-)
It's a tough call. The D is more capable, but DS is fast and light and a great bargain. If is said Canon or Nikon on the prism it would be a mcuh bigger success.
