Review:When I showed the iPhone 6S to one of my wife's friends, she got nostalgic. She waxed emotional about its predecessor, the iPhone 6 . It changed her life. Bigger screen, better camera, and Apple Pay . Everyone wanted these things. It was as close to a perfect phone as I've ever seen. All it ever really lacked was a better battery (Plus notwithstanding). I showed her 3D Touch, Apple's newest technology on these iPhones. She pressed on the hypnotically-animated lock screen, a swimming fish. She watched it dance under her finger. And yes, she was impressed. But when I showed her everything else 3D Touch does, she said, "I'm not sure I'd really use this." This year's follow-up iPhone, the iPhone 6S, doesn't improve on that battery. And its newest features aren't as instantly game-changing, at least not on the surface. That's obvious: it's an S-year iPhone, and Apple always uses these subtle every-other-year S upgrades to tw...