Okay, so you hold a two handed wiimote? I hope the window thing allows us to see either a different overlay (like maybe xray cam, or extended pseudo reality by pointing it outsite the tv screen edges) becaus eotherwise that would be clunky as hell.
I'm sorry, I didn't realize that you can't see any pictures of it.
It looks like a wacom tablet, wide and flat, with a 6 inch touchscreen in the middle. There are traditional buttons on the right hand side, a d-pad on the left hand side, and dual analogs on either side above the buttons and the d-pad. There are also L and R buttons on the top, and L and R triggers underneath. It is easily Nintendo's most conventional controller to date, if you discount the abnormally large touchscreen in the middle. If you ignore the touchscreen for the moment, it would be easy to see people playing conventional XBox 360 or PS3 titles with this new controller.
At the same time, this controller has all the same accelerometer features as the original Wii-mote. It also seems to be able to detect specific orientation in relation to the television screen. It streams video from the WiiU console without detectable lag.
They announced that Arkham city is going to be released on WiiU. I can already see about a dozen interesting ways in which you could use this controller for that game. You could use the "window" feature to inspect scenes with detective vision. (instead of swapping out the overall view, just hold the controller up)