Well I have used the iPhone 6S Plus over the weekend and taken a number of photos now. Bit by bit I am beginning to see the strengths and weaknesses.
First the photos. Remember, clicking on each photo will bring you to my Flickr account. There you can view the full size.
These all look amazing, except there are some limitations that I spotted. Despite near perfect weather, unless I got closer to my dogs, which in these shots I was unable, they are not as crystal clear, and cropping in closer does not help matters. The LG G4 would have nailed a shot like this and allowed me to crop in too without losing too much picture quality. However, the overall balance and picture reproduction is stunning. The panoramic shots are really impressive. The shutter speed of the 6S is super fast and even allows a burst of 999 shots. 4K video is better IMO than the LG G4 and just ahead of the S6. Lower light goes to the G4 and S6. The front selfie screen flash works very well. Live photos are superb. Just love the extra motion as I browse through the shots. Brings the moment back to life. The other aspect of the iPhone is reliability. It is so great at getting the shot correct first time every time.
Before I got this phone, IMO, the LG G4 had the best camera for stills. And I still believe it does with all the built in manual controls, RAW and its overall ability to find the light with its f/1.8 vs the iPhone 6S Plus f/2.2. However, the G4 loses out to video quality and other some other shots like panoramic. Of course, a phone is not always just about the camera!