My last smart phone was a blackberry.
I found it hard to do much real work on it. Other then using it for email I mostly used the internet on the blackberry to read things.
Hard to even read something on a small screen.
My last cell phone upgrade I skipped getting a smart phone and got a basic phone that will still let me do emails.
This iPad seems like a extension of my laptop and with 3g built in I can get online anyplace there is a cell signal.
Also with cloud computing (mobile me, iDisk and Dropbox) I can keep the iPad synced with my laptop and store service manuals online just like I would store them on a hard drive.