Very thoughtful piece by Walt Mossberg for Re/code:
Just because we or other writers say “this is the best iPhone yet” doesn’t mean you need to run out and get it. It may indeed be the best, and yet not worth it for you.
Some tech products just don’t benefit dramatically from upgrades, depending on how you use them. I personally believe that’s one reason why the upgrade cycle has stretched out for laptops, and seems to be longer than once imagined for tablets. Newer models are certainly better than older ones, but not so much better that they justify spending more money.