Here is comparison between my new space gray iPhone 6s plus and my old iPhone 6 in gold. I compare size, weight, thickness and colors. Check the video below.
Of course the iPhone 6s plus is bigger and heavier, but the new force touch display makes it a tiny bit thicker too. Personally I wish it was lighter, it's almost too heavy to be used with one hand. Hopefully Apple will make the iPhone 7 plus lighter again. Maybe with another material or something. And I also wish that the iPhone 7 plus also get an even bigger display by removing the Touch ID button. That way it can get a bigger display in the same sized phone.
And I actually like the space gray color on the phone, it's so nice to have a pure black front. But I think I still prefer a white front on the iPad.
Here is my comparison between my old iPhone and my new one:
Watch related videos from the Hands-on playlist.