It really, truly depends on which phone you get.
I really appreciate the virtual keyboard on the iPhone. It requires learning like any virtual keyboard, but the screen is very accurate and the layout is comfortable. I type faster on an iPhone than on any physical keyboard.
Many other phones don't necessarily have te same advantages. Most Android phones do well, but there are a lot of phones with resistive (pressure-based) touchscreen that are nasty to use if they don't have hardware keyboards.
Before you rush out and get anything, wait to see what Apple announces on Monday afternoon. Even if you don't want a brand new iPhone, it's expected that the iPhone 3GS will drop to $99. That's a very good deal for this class of phone.