Apple's iPhone 6S pitch was 'the only thing that's changed is everything', highlighting that it knows that, at least design wise, this is a phone looks an awful lot like the previous model of the Apple iPhone.
It makes sense that Apple would try its hardest to show that, despite the handset looking identical to the iPhone 6, there have been loads of changes under the hood that make this an attractive phone in its own right.
The chassis is stronger, the camera sharper, and there's even a completely new way of interacting with the screen. On paper, it's an impressive upgrade.
If you want a new iPhone, I'd recommend the Apple iPhone 6S wholeheartedly, especially if you're jumping from a 5S. It's got a great interface that's only going to get better, and the overall package is still excellent, especially for the price.
The iPhone 6 and 6S might look identical from the outside, but their internals are vastly different. The 6S not only adds the cursory tweaks, but also several key features, including a substantially faster processor, higher-resolution camera, live photos and, most notably, 3D Touch screen technology. All of this makes the iPhone 6S more than just a shinier iPhone 6.
Apple has upgraded the camera to use a 12-megapixel sensor, rather than the old iPhone 6's 8-megapixel model. Of course, the big difference is that you get more resolution, which means more detail in images. Exposure control is pretty similar to that of the iPhone 6, which isn't a huge problem as that phone generally picked the right automatic settings to capture a scene.
Testing the phone outside, I found that test shots were generally very good. Leaving the phone on its Auto HDR mode, I found that it managed to capture challenging shots, such as the contrast between dark streets and bright sky pretty well. When compared to its nearest competition, the Galaxy Samsung S6, Samsung's phone produced truer colours and its higher-resolution sensor captured more detail, but the iPhone 6S seems to process the image more, sharpening the picture. You could say that the Galaxy S6's image is more true to life, while the iPhone 6S produces a slightly hyper-real version. Neither versions are wrong and both produce excellent photos, so this will be a case of personal preference.
You have to look at a smartphone as an overall package, with it being the sum of its parts. Taken like this, the iPhone 6S is a great smartphone: it's staggeringly quick, it's camera is very good, 3D Touch is a real improvement and iOS 9 and iOS 10 are brilliant and slick operating systems. Taken like that, anybody that buys this Apple phone is going to be incredibly happy, it's everything the iPhone 6 should've been!