It's just one person's experience, but Amy Tiemann recently described her disappointment with the iPhone. Her conclusion:
It turns out that combining multiple functions into one device isn't always more convenient. For me, a Blackberry Pearl plus an iPod Nano seems to be the best combination. I need basic online access on my smart phone, but I don't browse a lot or compose a lot of e-mail on my Pearl. I either call back, answer e-mails from my desk, or if I am traveling, I have my laptop with me.Recall that Laura Ries stubbornly predicted that the iPhone would fail (after some initial success) because it is a convergence device. The jury's still out, but Amy Tiemann's experience is an interesting data point.