“I originally bought a generic 5v adapter and was running into issues with my Pi3. It was displaying a lightning symbol at the top right of the screen, which indicates undervoltage. I bought this 5.1v one and my problems went away. Looks like as the Pi3 ramps up current, the voltage drops to below 5v with the older PSU, this one drops to 5v which is the required voltage.”
“Just started the exploring of the pi3 and bought this official power supply to use with it. So far no issues. Has the correct power output to power the pi and external HD.”
“I had been digging through my man draw of plugs / cables etc trying to find a power supply that would solve the under voltage warning. Every power supply I owned did not seem man enough to power my pi 2 and touchscreen. Though I would give the official power supply a go and... all issues have gone and the pi even boots quicker. In summary if you need a power supply for you pi, just get this one, it just works!”