I think at this point everybody knows Wii U has more horsepower than 360 and PS3, with the main problem being that the system is selling so awful that budgets are the one big road block.
We can see how this affects visual comparisons, with GTA V simply looking better as a whole than X due to the massive difference in budget. X does in fact seem to have more advanced lightning, and is running at 1080p (right?) so if GTA V was made for the Wii U it would look noticeably better than 360 and PS3 versions just like Bayonetta 2 looks better than any Platinum game on HD twins and runs at 1080p 60fps.
In a way, it's pretty impressive how such a modest but calculated hardware improvement over current gen can produce significant results on screen. What's not nearly as impressive is at what cost it's being sold as.
Wii U being capable of DX11 equivalent features and Compute Shaders, when said it like that is disingenuous. Truth is DX10 has been capable of tesselation (instanced) at least since
2008 . Same for compute shaders
on DX10 hardware.
For a wider perspective on these things:
ATI Toy Shop Demo -
Read as how ATI in 2005 was already pushing for GPGPU, as they use the GPU for water simulation. Or how the
360 GPU could be used for physics.
It's not about being able to replicate or support certain features, it's about the hardware being designed to make them feasible in real time. AMD and NVIDIA strive to address bottlenecks that prevent some of these features to work in tandem, and allow the developers to actually put them to use.
AMD's solution is the
APU HSA design, which is being employed in a more advanced and matured fashion on the Xbox One and specially the Playstation 4 (GDDr5 became ready earlier than AMD anticipated, ESRAM was the previous short term solution to HUMA bandwidth limitations).
In short, Wii U is neither architecturally designed nor does it have enough processing power to actually take advantage of many of the features it theoretically supports. At least in the sense that it's able to actually put them to work, together, in a game.