Claiming you can do truly multitasking because it has 2 displays is ridiculous, but that's not the biggest issue in my opinion. More of a problem is that whole vision of this tablet is made on old technologies presented in new form. Ooh, they also added pen!
Sort of like best use of radio, when it appeared as new media, would be reading newspapers.
I bought a Tablet PC -- a $1500 item at the time -- so I could do digital art with it. I'd like to do the same with a lightweight and cheap device with a nice battery. Right now I can't because all tablets (except certain Windows tablet PCs) are designed around point-and-grunt (and no, those little rubber styluses aren't good enough).
Tablet + pen = 2 hands busy, you've lost most of your comfort and mobility advantage compared to a netbook user.
For the narrow niche of applications which require drawing on the screen, you can simply design a capacitive pen for iPad; you'll never amortize the development of a dedicated hardware, let alone OS.
There are tablet PCs which accept both pen and finger input.
And you pretty much need a Wacom-style digitizer in order to register pen strokes with the precision and pressure sensitivity required of art or handwriting applications.