Actually, an iPhone is a tiny iPad. And an iPad is a tiny limited Mac with a touch interface.
I don't have an iPad, and the iPad can't run World of Warcraft. But a PC can't run Angry BIrds either, for $1.99.
People comparing NetBook functionality with the iPad are mostly missing the point.
I think consumers are sick to death of the maintenance and problems they run into with larger, more complicated PCs. I would get ulcers if I gave my mom a Win OS laptop, just waiting for that "thing doesn't work anymore" call and the support visit to reimage her machine - but I wouldn't hesitate to give her an iPad.
I think the things the iPad does best are the things most people want to do with their limited-capability PCs. Browse the web, handle your email, play a few games (those that don't require a doctorate in advanced game theory), look at your pictures, play a little music.
I don't have an iPad, but I do have an iPhone. When I need to transcode video, I do it with my MacBook Pro, and I'm not about to give that up.