Although I am a long-time Apple supporter (my wife's Apple //e is still in the closet), my first iPhone was an iPhone 4S on Verizon. (Part of the reason I waited is that I didn't want to leave Verizon.) With the announcement of Apple's trade-in program (which just adds to the existing trade-in options) and the expected announcement of the iPhone 5S, you might thing I would be thinking of upgrading. Nope.
I'm old school when it comes to cell phones. Back before smart phones, I would typically get a new phone every three years with a two year contract. Some of the feature phones were not built to last three years and I remember replacing my Motorola Razr before three years because the keypad wore out.
I'm looking forward to iOS 7 which will give my phone a new look along with new features.
I'm going to hang on to the 4S until Apple no longer supports it with the latest operating system OR a new iPhone comes out with a feature that I just have to have. It could be a while.