There's no question that the battery life is poor on an iPhone, but that is the only major draw back.
We have exchanger servers on each of our sites, and to use blackberries we would have had to purchase blackberry enterprise server for each site, $$, new server hardware $$, and would have had an additional application to support. This isn't required when using the iPhone for mails.
Anyone who says that you can't type as quickly on a touch screen may not have used one for long.
I don't think you can say tha the iPhone isn't suitable for business.... for me, it is suitable, and preferable to using blackberries. Unfortunatley, the phone providers don't seem to agree, and there are no tarriffs available that are aimed at business users.
Data roaming is horribly expensive (which is a real drawback)
Vodafone are officially offering the iPhone from March 25th, but they are maintaing their cosy cartel with 02, and there's not much difference in pricing in the tarrifs.
Can you tether with a blackberry? (Use the blackberry as a modem to get internet access on your laptop)?