I don't know about that. It all depends on what the user wants.
My iPhone 4 does everything I need. Call/text/camera/browse internet. It's been through hell over the past 3 years and works fine still.
I will admit the only reason I bought iphone 4 originally was because of of how much I enjoyed my imac over a PC. Alot of things have changed since then, though I'm still happy to not have to deal with windows error screens and misc problems. Whenever I buy my next phone (when my iphone 4 eventually dies) I'd be open to an android phone.
If you are happy with your iPhone 4... You have NO idea what a new cellphone can do. Not to get too nerdy but an iPhone 4 today is like watching tv without HD. Once you try it you can never go back.