First the good news - it's light, compact, reasonably capable for typing, and it has enough battery life for you not to be forever worrying about where your next power socket's coming from. These advantages alone are sufficient for me to take the iPad seriously for note-taking and for document viewing and manipulation, and to stop using the MacBook Air as the thing I carry around all the time.
You can check out, but you can't leave
But the bad news is that - in this iteration at least - the iPad is a conflicted machine. It's a media consumption device, and if it's just that it's an expensive one. Not that Steve Jobs is likely to go broke by selling expensive toys, as the sales figures remind us. But alongside this it has a capability as a productivity tool, and it's here that the problems start to tumble out. That doesn't mean it doesn't have a value there, but it does mean that it has considerable potential to become an infuriating device to use.
So let's look at the infuriation: exchanging files, the iTunes tether, and the iPad's status as a big iPhone that can't make phone calls. These are all related. Apple won't let you anywhere near the iPad file system, and each app on the iPad has its own storage space. So if you've been using a file with one app, there's no way you can use it with another app without exporting it and then importing it into the other app. And how do you import and export?