GH3 "new 16MP multi-aspect ratio sensor"

It probably doesn't matter. In 4:3 and 1:1 there ist no difference (4608 x 3456 and 3456 x 3456); but you loose some pixels with the 3:2 and 16:9 ratio. Nevertheless I assume that the new sensor performs distinctly better, so in practice we will see improved image quality.