Here's some E3 buzzkill for you: it seems the battery in Nintendo's Wii U control pad only lasts for 3-5 hours.
That's...wow. That's less than a lot of you would spend during a serious session with a game.
This is going to be a problem given the nature of the controller; it's one thing to have a pad plugged in while it's sitting in your lap and charging. If you're tilting it and moving it around the room, it's going to create problems.
Those aren't rumoured specs, either; they're official figures supplied by Nintendo. Bummer. Even worse is that they're estimates, with Nintendo saying that the screen brightness and "usage" may decrease it even further.
Nintendo also said that it takes around 2.5 hours to charge a depleted battery.