We upgrade our iPhones every time we're eligible for an upgrade (or wait a few months if a new version is coming out soon). I'm eligible now, but waiting. Our old iPhones (with no phone service) get passed down to the kids essentially as iPod Touches. The 3 year old is ready to get his own, and the 7 and 10 year old are looking forward to newer ones.
I only use my iPhone as a phone. And to check email. And to browse the web. And as a calendar. And a rolodex. And a camera. And a photo album. And basic photo editing. And to check the weather. And as a GPS. And to find cheap gas. And for subway maps. And to check stock prices, access my bank, my credit cards and my investment accounts. And to find good restaurants and restaurant deals. And to check movie times, find Redbox locations, listen to music, stream Netflix and Amazon Prime video. And to listen to podcasts. And to read books and the Bible. And to compare prices when I'm shopping in a store. And to shop at eBay and Amazon. And to review sales at Sams and Costco. And to organize our travel. And digital boarding passes. And flight tracking. And for travel guides. And to search for flights. And to look things up on Wikipedia. And as a dictionary. And sometimes to check sports scores. And for a Spanish/English dictionary. And to read Drudge, the WSJ and USA Today. And to watch movies and TV shows. And as a calculator. And to take notes. And as an alarm clock, world clock, and timer. And as a flashlight. And as a Roku remote when we misplace ours. And to log into various PCs of ours. And for dozens of games for me and the kids. And to check Disney wait times and details. And as a credit card terminal. And to view incoming faxes from eFax. And to look up Per Diem rates. And to monitor newsletter performance. And to view incoming orders. And to convert web pages to PDF files. And to make "fan" sounds when we travel without our fan. And to identify songs that I like.
If I lose my iPhone or the battery dies, I'm lost without it. There's not much I don't do on it.