If all you do is type all day, then a tablet is just about as useful as a rock (not even as useful as a nail really...)
But like sparkleytone's example, people who do things other than type all day still have to resort to pen and paper - anyone used that recently?
There are so many uses for a tablet. All you nay-sayers need to get outside more often; stretch your backs and legs a bit. The huge adavantage in mobility they offer soon becomes apparent.
It's not a rich man's toy. They are so many industries where people don't sit at their desks all day using a keyboard. So many of these could use a tablet, instead of the notebooks (yes - paper ones) and photocopies and folders to store all those little bits of paper...
As for using a laptop instead - has anyone here ever tried to stand up, holding a laptop in one hand and operating it in the other? Trust me, it's far from useful.
Teamed up with properly designed software (i.e. not a word processor) a tablet could in may ways replace the huge wads of paper that many of us are still forced to carry around when we need to scribble or present something.
And if anyone can do this right, it's Apple.
<edit: I'll just qualify the above by saying it's got to be priced better. The reason no-one is buying them now is largely to do with their price - often more expensive than a laptop

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