As with any console (and this really should be the criteria used by most people picking their games consoles) I'll buy it if a game comes out for it that I really want. Right now the only thing that interests me is Tekken Tag Tournament 2 Wii U Edition and since I already have the 360 version, that's not nearly enough to sell me on a console.
I imagine there will be quality Mario and Zelda titles on it eventually, though saying that, I've somehow managed to not play the big Mario and Zelda titles on the Wii yet, so I have plenty of that stuff to get through anyway... I should probably play those soon. I have way too many games in my backlog in general, I guess that's not really a bad thing.
Maybe I'll just play Mario Galaxy 2 and Skyward Sword and forget about the rest of it, I dunno.