I didn't pre-order and iPad; there's an Apple Store pretty close to my apartment so I plan to give it the once over before buying one. But I am sure, even with it's shortcomings, it is going to be a huge hit.
Not withstanding the price point, the target market is as large as the number of apps it can handle. Cost aside, I can see my 90 year old father-in-law preferring watching movies on a lap-held device than his TV; I can see my parents traveling with one and I can see my kids using it as a gaming device. And as others have pointed out, why buy a Kindle if an iPad exists? Apple will be first to market with this kind of device. It's going to be huge.
Alacra's Research Recap blog, using Alacra Pulse, recently posted Analysts Ramping Up Forecasts of iPad Sales. Morgan Stanley's Kathryn Huberty has forecast that Apple will ship 6 million iPads in 2010. It's going to be a category killer in a category of its own design.