With this power supply, you can power the Raspberry Pi 3 at full load as well as up to 1.2A across the four USB ports.
The power supply still has about 0.5A of output power to spare, so even at the maximum current supported by the Raspberry Pi 3, the power supply is not at its absolute maximum.
It is also ideal for use by anyone over-clocking the Raspberry Pi which causes higher power requirements that a lower power adapter may not be able to supply.
