Do you want to touch the screen?
ken: I've never used one, but every review of the Cintiq I've ever read is roughly "Best device ever!  Should have bought it years ago!  Worth every penny!  From my cold dead hands!".  This suggests to me that for at least a significant minority of use cases, more direct manipulation is quite useful.You admit it's good for phones but bad for "normal computers".  But your phone is more powerful than your PC was 10 years ago.  Lots of people have already given up desktops for laptops; is it so hard to imagine one day many people will have given up laptops for even smaller devices?I think it would be great for collaboration.  Two people and one screen is OK, but you either have collaboration software (complex) or have to share input devices (awkward).  A touchscreen bring back the immediacy of sketching something out on a whiteboard together.As you point out, the interface will need to change.  (When I was typing commands into my terminal, I never thought "Damn if only I could drag a bar of soap around my desk to do this!")  The mouse is a local maximum.  But it's a chicken-and-egg problem: you can't write software for hardware that nobody has.  So if people want to build touchscreens, I'm all for it.  Maybe somebody will build an interface for them that doesn't suck.