My First lasted 4 years.
[2G, VGA Camera]<p>2nd Phone lasted 5 years.
[3G, GPS, WiFi, Bluetooth, Radio, 5MP Camera]<p>3rd Phone 2 Years and counting.
[4G, GPS, WiFi, Bluetooth, Camera + Front Camera]<p>It's a simple pattern. Every new phone buy should be a major Technology Upgrade, not just specification upgrade. So Minimum Requirement for my next phone will be [5G]. Hopefully within next 2 years. :)