I think the iPad is a great thing. As long as your conscious about the lock-in and can be in peace with the fact, it's a nice tool. People try to make it more than it should be, and then criticize it for not meeting their expectations. Like no webcam, no USB (although there's an adapter) and various other shortcomings when compared to a netbook or a normal notebook.
The way I look at it it's a browsing machine for the couch. To browse a few site, see a few videos, read newspapers, check some email, and from time to time show a few photos if required.
It's useless for music (because at home I have my HiFi and when travelling a small ipod), and I don't think its a good book reader either. It's also very little fun to game with (kids may see this differently). It's really just for surfing and a few things left and right of that.
Most people, and I assume close to nobody, really needs it, but it's nice to have because it's convenient to use. It's like you may have a car for the family, and would love to have a convertible just for the sunny days and when you're on your own. You actually don't need it, but when you can afford it, why not? And nobody's going to criticize you for it.
So it's with the iPad, just on a smaller scale (500 USD)... I think I'm going to get one.
oh, and:
Cheers,
Frank