Samsung has increased the pixel pitch from 1.12um to 1.4um in its latest flagship smartphones Galaxy S7 and S7 Edge, reducing the resolution from 16MP in the previous generation to 12MP now. The new sensor feature Dual Pixel AF (all pixel PDAF):
"The advantage of the Dual Pixel image sensor in the Galaxy S7 is most evident when taking pictures in a low-light environment. The newest smartphone model is equipped with 1.4um pixels (a 56 percent increase in size compared to the Galaxy S6) and a large F1.7 aperture (which allows for 25 percent more brightness). Combined, these features enable for 95 percent more light compared to its predecessor, which subsequently results in a much brighter and sharper image. Furthermore, the new model employs autofocusing at considerably faster speeds, allowing for faster shooting."
The company's Youtube videos emphasize the PDAF speed and low light capabilities of the new camera: