I stuck my head right into the tunnel in one of the caves. The biggest improvement from DK2 to Rift are in descending order: positional tracking, audio, framerate and then image quality last.
That's disappointing. I was hoping for the opposite. The consumer level software looks and plays well on the DK2 so far. I am impressed. Tracking is still a bit janky but great nonetheless. I wonder if the tracking camera and touch controllers will be sold separately? That would be nice if I could supplement my Vive with Rift stuff if wrappers are crappy.