As someone who works in IT and supports 400 iPhones, the typical life span I am seeing over the last three years has been 12 to 24 months before they start having major problems and need to be replaced.
I think mine is already dead! At least from the looks of this video I made of my problems with iPhone6+ rebooting on it's own at very unfortunate times.
As someone who works in IT and supports 400 iPhones, the typical life span I am seeing over the last three years has been 12 to 24 months before they start having major problems and need to be replaced.