It's one of those devices that you didn't know you couldn't live without until you got one :P
Just like the iPhone. So many times you hear people say they didn't see the need for all the stuff the iPhone could do, until they bought one. Then suddenly they are checking mail, playing games, doing banking, buying stuff via their phone.
For example It's difficult to fully appreciate the iPads ability to REPLACE magazines and newspapers in your home until you have it in your home. Or to replace your photo album, now you will just use an iPad to show friends photos. There are lots more examples, with the ability to have apps it can do all kinds of things we haven't envisioned.