The low light scene is shot with Auto White Balance, to show how the camera's JPEGs look under artificial light. Any 'keep warm tone' options are left at their default setting.
The low light scene Raws are processed to demonstrate the capability of cameras in low-light shooting situations. Noise reduction is minimized and the white balance is neutralized to reveal blue channel noise. The black level is lifted to prevent noise being hidden by clipping. A standardized amount of sharpening is applied in Photoshop.
At low ISO you can see that the Df's higher res rivals significantly out-resolve it. The Sony Alpha 7 looks sharper but the Nikon D610 (using a similar sensor) is producing the more convincing rendering.
At higher ISOs the Df's JPEGs are showing more noise in this, more challenging, lighting. However, look into areas of fine detail and you'll see that it's also producing a more realistic representation than its rivals.
Move up to the highest ISO setting all its rivals can match and the story is similar - with the Df showing quite a lot of noise but also some detail and hard edges being retained. However, looking at the Raw files (with noise reduction minimized) it's clear that, while the Df is doing well, it's not that far ahead of the Canon EOS 6D. That slight advantage is maintained, even when the images are reduced to a common output size.
Overall, then, the Df is capable of excellent low light images, but its advantage is not massive - especially when compared at a consistent resolution. And, of course, in bright light it can't compete with the resolution of its less expensive peers, let alone the higher pixel count models.