Yeah, I own a 5S and I have almost no desire to replace it other than to upgrade storage to 128 Gb. Even after 3 major iOS upgrades, all of my most used apps open close enough to instantly. - the time it takes to pull the phone out of my pocket is the biggest bottleneck at this point.

If I'm going to spend > $600, I expect my life to improve a little bit. I'll probably upgrade to the 7, mostly because I've gone without a case and have had some dings that do impact functionality, but I hope to go 4 or even 5 years with my next phone.