I've set up a few. I'll have one myself soon. Now that it's out, I see a lot more practical value than I originally did. Typing on it is actually pretty good. But here's the missing links to it right now:
- No direct printing. There are a few workarounds and 3rd-party print methods, but no Apple-sanctioned way to get print output to even a small group of supported devices. I don't think OS 4.0 will change that, either.
- The filesystem isn't shared between apps yet, and there's no true wireless server access or file sync. So the killer app would be a local (maybe as an app written in HTML5) app that has its own cache in local filespace that syncs to Google Docs and has a desktop component that does the same sync. That puts all your real storage in the cloud, with the iPad mainly caching so that it can be used offline. Internet isn't quite ubiquitous yet.
Resolve these and the iPad will be the biggest thing ever.