Wii U looks pretty awesome, but I'm not sure how well it is gonna jive with these "hardcore" titles Nintendo is showing off. I can see the new controller showing a bunch of the HUD elements, or perhaps quick menus or inventory. It screen would be the ultimate context sensitive button, the perfect pop-up for multiple options. But I think the tablet display would be near useless in an combat situation. No one is going to play Darksiders or Ghost Recon in the Shield Pose. The controller will be in everyone's lap just like they are now. I think it will be very tough to have necessary information in a place that forces a player to look completely down, away from the screen.
What I think it would be great for is adventure games, LA Noire specifically. Imagine no HUB elements on screen at all. All those elements as well as menus could be shown on the tablet. The notebook could be entirely on the tablet, leaving the suspect on screen free of any prompts or instructions.
The tech looks cool and I'm certain it will be used in amazing ways, I have serious doubts they will be able to bring the hardcore audience back into a Nintendo Console.