While the power difference is pretty major on paper, I doubt it's going to have much of an effect in the overall look of games. We've hit such a point of diminishing returns, and we are so constrained by the amount of money thrown at a game, that 50% more power in the GPU is unlikely to have a massive effect on how the games look. I mean, this isn't a generational leap between the two systems.
I'd be more worried about all the extra complexity in the Xbone. How much are devs going to have to finagle with those helpers, and moving things in and out of ESRAM? Is that going to be a major issues (Legitmately, I don't know here) or will they have to rely on higher level libraries to help?
Similarly, the service/featureset of the XBONE looks like a MASSIVE clusterfuck. If the XBone fails, it won't be because of 33% fewer compute units, or lower badwidth RAM.