Even if those are JPEG, I am really impressed! Not only do we have 1-2 stops better in ISO performance, but colors rendition and details seem better at all ISOs as well. I htink it is unrealistic for poeple to expect the low ISO (100-800) of the 5DmkIII to have a smuch details as the D800. In every like for like comparison I saw the new mkIII seem better then the mkII and worth upgrading in my mind.
Yeah, it's great if you shoot JPEG, no doubt. Detail is definitely attibutable to the new RAW conversion process, but I'm not sure about the color rendition. And that's why I've been shooting RAW for years, the benefits over in-camera processing have been very evident.
But again, those are not RAW, so maybe if you take those same 5DII files in RAW format, and convert them with DPP into a JPEG, you get similar results to the 5DIII JPEG conversion done in the camera itself.