I think CoD: Black Ops 2 it's a good example of the graphical improvement, isn't it?. X360 and PS3 first CoD:BO ran at 600p and 540p respectively, while the CoD:BO2 will run at 1080p at Wii U. Taking in consideration that the first generation of games is always not well optimized, i'd say it's a good demonstrative about the wii u power
I don't think it has really been 100% confirmed at this point that it runs at 1080p, despite what PR has said thus far (full HD). Regardless, I don' think CoD is the best benchmark for a system's capabilities.