Talking through the Wii U specs with my children (not something I often do but they were asking about it) led to them suggesting we did a similar test of controller battery life not a bad idea at all I thought.
The front of controller features bass, treble and volume knobs, a power toggle, LED indicator and a 3.5mm auxiliary jack, while the back features a secondary 3.5mm jack, a powered USB port (allowing for the hookup of Bluetooth-enabling dongles, for example) and a toaster slot for the current and previous generation of AirPort Express routers.