Tony, if it wasn't for the auto-correct, the iPhone keyboard would be completely useless for me.

I can type perfectly fine on a BlackBerry though, despite having had barely any experience with one - I have much more typing time on the iPhone and iPod Touch before it.

I've discovered that the biggest issue for me isn't the keycap size nor the fact that they're not tactile. It's the ability to hold the phone solidly while typing. On a BlackBerry, and I assume other devices with similar fixed keyboards, you can overlap the meaty base of your thumb over the keyboard as you grip the device without a problem. On a touch-screen device this doesn't work because touching the screen with those parts of your hands registers input, screwing up the ability to type.