... on the specific use. Why is a tablet better than a keyboard/mouse? Sometimes it is, sometimes it isn't. Why is a CAD station tablet or a pressure-sensitive tablet/pen combo (such as those from WACOM) better than touch or a keyboard/mouse? Depends on the application.

For everyday use (and I mean both basic "I want to get email/surf this web thing/look at that facebook thing" and at the office typing/creating spreadsheets/etc,) it's not adding anything better (yet.) However, I'm sure there'll be some areas this will be an absolute breakthrough - 3d imaging, perhaps, taking tablet-esque swipes/pinches/zooms to the next stage, for instance.