In a recent interview Gearbox has said that with the Wii U we will be seeing textures at resolution not yet possible with current gen HD consoles. Also, Epic games has come out and said that the Wii U is "opens up some doors that weren't open before on current generation consoles because it is going to be a powerful box."
There is a new mod for Crysis 2 called "Blackfire" which improves the textures even more so than Crytek's own update for the PC version of the game. If you skip to about 1:25 in the video you will see a good example of textures that are not currently possible on PS3 and Xbox 360. Will the Wii U have games that have graphics similar to this? I'm betting on yes since the features that will be present in the Wii U's GPU are all the same as a DirectX 11 graphics card but being rendered with Open GL. I'm excited to see what Crytek and Epic Games can do with the Wii U's expanded graphical abilities!