For now, I can forgive the bad quality pictures simply because I feel as if the person who took them doesn't know what they are doing. Filming vertical video and taking pictures in low light without checking the focus or seemingly doing anything but pointing and shooting. This is a typical smartphone user, just doing what comes natural without any consideration for how it may affect the picture quality. There's nothing wrong with that but if you want better picture quality you will have to try harder.
Hopefully when we have the phone in our hands, with a little bit of care in the way we take pictures, they will come out better than this.
For everyone who says "It's a smartphone camera, what do you expect", take a look at some of the shots from a Galaxy S6 & LG G4, even in low light they do very well for smartphone cameras, very much better than what we have seen here so far. Now she did get a 6S not a 6S Plus right, the 6S doesn't have OIS so it may not do as well as the 6S Plus in low light. Comparatively, the Galaxy S6 and LG G4 both have OIS.
The Geekbench score looks great and I'm very excited to get my 6S Plus, but my pre-order is on a 3-4 week wait