I sold a laptop to buy my first iPhone, and I managed for quite a while with just that and a Mini at home. I could do nearly anything I'd ever want to do away from the house on it, and convenience of having it in my pocket at all times couldn't be beat. However, I eventually traded out the Mini for a new laptop because I needed to be able to get out of the house occasionally and write, really write, on a real keyboard. It's a particular need of mine because I like to sit down and work on long essays, but that's a function that a PDA/phone will never be able to address. Even with a Bluetooth keyboard, I'd be loath to do much more than email and basic input on such a small screen. That form factor is perfect for consumption and communication (i.e. 90% of what we need to do on the go), but not always creativity.