‘ve had my iPhone for just over a week now (I know, with the imminent release of iPhone 3.0 I haven’t exactly been an early-adopter on this one) and I’ve figured out why it’s been such a success.

It’s not because it’s sexy and shiny and plays music and lets you watch YouTube and play great games and read blogs and twitter.

It’s not because the touch screen keyboard is pretty good and the accelerometers mean it automatically rotates the screen when you turn it over.

It’s not because the location services and built-in GPS mean it knows where you are and can do cool things with maps and friend/restaurant locators.

It’s definitely not because of the quality of the camera or the life of the battery or the slightly flaky exchange server push mail integration.

Nope, it’s more fundamental than that.

Using the iPhone is relaxing.  Seriously.  The gestures, the screen transitions, the responsiveness all combine to make a calming user experience.  No other mobile device manages to achieve this: The Blackberry is a tense fiddle of scroll wheels or mini track-ball followed by cramped two-thumb typing, all Windows Mobile devices I’ve used are sluggish and require almost pin-point accuracy with a small stick and every Nokia, Motorola or Sony Ericcson I’ve ever used has had a counter-intuitive interface a predictive text system that has made me want to smash it against the nearest solid object.

Just about the only thing that’s frustrated me about the iPhone in the last week has been level 64 on Blocked.