The iPhone gets really hot. Especially near your ear. Ouch!
After fiddling with it for an hour, I know how to work the iPhone better than the Nokia I had for the past 2 years, even though the Nokia has far fewer capabilities.
Not a surprise, but noteworthy nonetheless: iPhone’s Mail has no spam filtering whatsoever. You’ve either got server-side spam filtering or you’re stuck wading through the dreck.