Considering I’m coming from an iPhone 4s running iOS 9 (virtually unusable), the 6 is a massive upgrade in every way. It is noticeably lighter and more comfortable to hold than the 6s, in my opinion. And I feel only a slight difference in performance. Yes, the 6s feels faster, but not by much. I’m running iOS 11.3 and it flies on the 6. Haven’t had any slowdowns at all. My only concern is that it will show its age much quicker than the 6s. Considering screen size, benchmark scores, weight, build quality, screen quality, and operating system, I feel like this was the best decision for me. So am I nuts for buying such an old phone in 2018.