It's very interesting this comparison that Digital foundry did that got Neogaf all a flutter. DF's PS4 capture was washed out, looking not as sharp as the Xbone's. Then looking at other captures that washed out look doesn't appear to be there, so it's something on Digital foundry's end I guess.
They were thinking it was the PS4's software upscaler vs MS's upscaler, but that doesn't appear to be the case,. The Xbone's upscaler seems to sharpen things considerably at the expense of slight artifacting (Halo's),
and the blacks were crushed (Though from other captures, it looks again to be DF's methods)
What was noticeable is the framerate tests, where the Xbone went down as low as the low thirties in framerate at 720p, and the PS4 doing 900p and keeping a much higher frame rate. The PS4 also has soft shadows and ambient occlusion going on. The Upscaler seems to also bring out the jaggies more so in the Xbone version.
It's now painfully obvious that the PS4's GPU IS much more robust, but that Sony might have gone for software upscaling which means games that are native 1080p are going to look better than anything less than that.
However, Both versions look good, and both don't seem to dip below 30fps so it's all good. If you have a larger TV, the PS4 version is going to look better, a smaller TV and the Xbone might actually be sharper, but missing the effects that the PC version and the PS4 versions Have.