The Ace Attorney series doesn't rush you to make quick button presses or constantly look at both screens.
Or just be able to multitask a bit; which I'm shit at, but I've managed fine at any games that have some ocular trickiness to 'em. Although now that I've thunk on it a bit it would be tough to have an entire map on the tablet and use it without pausing in some sort of fast paced action game... That'd be comparable to looking down after you've acquired a target via gun sights, and then having to reacquire said target: a bit disorienting.
There's definitely a place for game data being on the tablet, though. You could go through menus while the TV-side screen is paused via touch screen and all that handiness, and in non-action games you could display a shitton of data on the tablet. RPGs, MMOs, and clearing on-screen clutter for many games in general would be pretty handy. Sort of like what Fire Emblem: Shadow Dragon does. The map is on the bottom screen, all the technical information on the top screen.
Ahhhhh, what I would like to see is "Pokemon: Dawn of the Magikarps" It would just be awesome controlling a squadron of Magikarps in your hands in the tablet. It will be a new era! =P
Back to reality, I just hope the games will be okay and not let the 3rd parties overcome with the movements of the controller.