Less time charging. More time doing.
Charge up to 75% faster.
In laboratory tests using a 3300mAh battery1, a Quick Charge 2.0 enabled device went from 0% to 60% charge in 30 minutes, while a device without Quick Charge 2.0 using a conventional (5 volt, 1 amp) charger achieved just a 12% gain in the same 30 minutes. A device with Quick Charge 1.0 managed a 30% charge in that time period.
1 Based on internal tests charging a 3300mAh battery using a  QC2.0 USB wall adapter (9V, 2A),  USB wall adapter (5V, 2A), and  USB wall adapter (5V, 1A), respectively. (February 2013)