Via Ars Technica, who was a bit frustrated by the lack of new information:
The new controller is an impressive thing to hold in your hands. It feels solid and comfortable, and nothing about it marks it as a weak link. The screen itself is bright and beautiful, much clearer than the screen on an iPad, and even small details of the games are able to be seen clearly. The controller’s speakers also do a good job of delivering information to the player via audio clues. I could easily see playing entire games without a TV, using just the screen on the controller.
You had me at “impressive.”