I have just purchased the iPhone 3G and can say that it delivers on usefulness and userfriendliness.
When you start using lots of the functionality provided by 3rd party applications, such as “TrackThing” which shows you your current speed and location, as well as the distance you’ve travelled since breakfast, the battery starts draining quickly.
If you browse the biggest and best websites, the battery drains off.
However, while the battery life is a concern, I have found using it normally you can have the phone running all day without any problems.
My recommendation is, if you want something that is easy to use, and you want to run your business from your phone at times, this device will do it. Easily. Buy it, do it now.
Just don’t browse the internet too much (you can zoom in using some clever but easy finger work), otherwise your battery life will go down as fast as the Lehman Brothers stock price has this week.