There's a lot of technical aspects that concern me:
1. Overall price. They're selling a system with graphical capabilities that are at least comparable to the 360. That alone will jump the price. I can't fathom the console alone costing less than $250. Combined with this controller, I could easily see that price be $400 or more.
2. Is it possible, and do they intend people to have multiples of these controllers? I'm thinking no, but that could jack the price up even more.
3. What's the battery life on that controller? I'd assume it's rechargeable, but considering none of the Wiimotes are, that can't be guaranteed. Even a good tablet only lasts 10 hours with the screen on, so something smaller like this, with cheaper parts might not even last that long.
4. Durability? I imagine, besides price, that they used resistive touch in order to make a tougher screen. Still, considering the fiasco with broken TVs and wiimotes, I can't dare imagine how many of these controllers are going to get stepped on, dropped, smashed, thrown, etc.