In my recent review of the iPhone 6s Plus, I noted that the new 12-megapixel rear camera was an improvement over last year's 8-megapixel unit mainly due to the fact that larger images would afford a bit more flexibility in terms of cropping and resizing.
As far as pure image quality, however, I wasn't able to spot much difference between the old and new sensor. According to testing from imaging specialist DxOMark, my observations were seemingly spot-on.
The publication gave the iPhone 6s (not the 6s Plus which includes optical image stabilization) an overall score of 82 - the same score last year's iPhone 6 earned and tied with the Sony Xperia Z3+. That's a solid score although there are several other smartphones that scored ahead of the iPhone 6s.
In first place with a score of 87 is the Sony Xperia Z5 followed by the Samsung Galaxy S6 Edge at 86. The new Google Nexus 6P currently sits in third with a score of 84. The LG G4, Samsung Galaxy Note 4 and the Motorola X Style are all tied for fourth place at 83 points.
In the photo tests, the iPhone 6s scored favorably in the autofocus, exposure / contrast and artifacts categories. Scores of 73 in both texture and noise categories, however, certainly didn't help matters. Noise was also an issue in video testing, as was a lack of stabilization.