You won't. Are you sure as a businessman, that you want a phone that stops working during an important phone call, because the battery is flat? And you can't do anything against it because opposing to other phones you can't simply take out the battery and replace it with a spare one?
There are many smartphones out there which let you go on the internet. That have decent screens, better battery life (+you can change the battery). They aren't that good as MP3/video player, sure, but then it's a business phone.
Well, I for one never have a spare battery, since changing the battery means downtime and hanging up during that important phone call. I bring a charger with me, so instead of 2 charges with downtime in between, I can keep the phone going almost indefinitely without interruption. So the iPhone wouldn't (for me) lost out by not having an easily replaceable battery.
I'd agree that the media player aspect is largely a non-issue for most business users, though the large capacity is a plus. (Actually, for my company - software for the media/advertising industry - a media playing phone would be very useful if the iPhone has some kind of video-out capability - easier to bring a phone to meetings than a laptop).
Whether 3rd party applications ever appear or not, the file formats that the iPhone supports will be crucial. Good Flash support is crucial, given how powerful Flash is becoming these days.
It appeals to me as a business phone (compared to my recent phones) because of:
- Fast, responsive UI.
- Larger screen for reading text.
- Large storage capacity.
- Visual voicemail (not having to listen through dozens of messages to get at the one that matters, oh yes!)
- Gesture based UI. (not having to click tiny buttons in the corners with my stylus to scroll up and down, then click a tiny button to go to the next/previous document).
- Likelihood of excellent integration with iSync/iCal for contacts & schedules (this is, after all, a Mac site).
Negatives:
- Lack of 3G - the biggie.
- No push email - though not a major issue for me personally.