One thing I appreciate about the Pre, especially after years of using a Treo, it the ability to use it with one hand (one thumb, basically). I can pull it from my shirt pocket and slide open the keyboard, which turns it on, in one smooth motion. I can then answer a call, respond to an alarm or alert of email, or initiate a task with a touch or swipe on the screen, or start a search or make a call (speed dial) by touching a key on the keyboard.
While some one-handed operatiion is possible on the iPhone, for the most part, it takes two hands to tango. And typing on the glass keyboard turns in to hunt-and-peck torture, compared to two-thumb speedery on the Pre.