I've been reading this for reasons NOT to buy an iPhone - although perhaps the thread title shouldn't have encouraged me.
I'm a die hard PDA user having started off with a Psion Series 3 in 199x, moving through a 3a, 3c, 5, 5mx, then a Handspring Visor, a Palm T3 and then a series of Palm TXs that kept dying on me but which I found so invaluable so as to be unable to do anything else but buy another. I'm on my third Palm TX now. I also lump around a (work) mobile phone that is (according to colleagues) brick like and well past its sell-by date. And I'm no great fan of mobiles though Mrs Mudtracker says I should have one.
Still there has been a constant internal monologue urging me to go and get one. Because: it runs the medical software that I use on the Palm, only better; it can access email on the go (both personal and work); I can waste time at work by browsing the YACF pages; etc.
Counter arguments that I have used in defence are that I don't live in a metropolitan area; I don't need an app to find the nearest Starbucks; that I lead a reasonably predictable life in a very rural area that doesn't and so don't need to know when the next train to Maidstone or wherever. I also don't have a contract mobile phone so it's an additional cost straight away (I have a cheapie tiny mobile PAYG that lives in the bottom of my bum bag and gets switched on and recharged every couple of months, and that's it).
However, when I read about things like Routebuddy, the Tesco finder, and now the Grauniad app, I find my resolve crumbling. Please someone tell me that a 3GS is not the answer to my every heart's desire. I do have a 1st gen iPod Touch that is slowly beginning to supercede the Palm, but obviously neither of them have the mobile internet thingy that the iPhone has (wifi hotspots being few and far between around here).