I use my iPhone more than anything. I use it more than my Mac, my TV. It's an awseome multi-fuction device. It's a cell phone, iPod, GPS, photo album, portable game, and email/Web in one little brick.
Some people just don't get it, and while everyone here obviously gets it, I don't think we each utilize the phone to the same extent. While I won't pay extra to upgrade early, if mine busted, I'd buy a new one whatever it costs.
Same for me, I use my iPhone all the time. I have a 16 GB 3G that a friend is buying. That will cover the cost of my 16 GB 3GS and new case. If the sale of my old phone didn't cover the cost of the new one then I wouldn't have done it. Especially as I'm saving to get married next year.