Highlights:
Basically, complaints from third parties are not due to technical limitations but due to lack of understanding of the system architecture. The poster seems to be a student who has spoken to developers who have Wii U dev kits.
"Optimized code for the 360 may run sub-par on the Wii U" But Nintendo builds very efficient systems that need to be taken advantage of.
"The performance will scale up considerably on proprietary engines I've been told. (much like the PS3, though even more capable)"
"As far as the lighting is concerned, I tried to describe having some fixed functionality in parallel to programmable shaders. What this yields is stable, predictable performance. This is especially important when rendering a seperate viewpoint on the DRC (display remote controller) from what is shown on the main screen" - Meaning lighting effects don't have to be a programmed shader in the engine, but are built in to the Graphics.
"There is definitely a DSP" - Digital Signal Processor, probably for dedicated audio.