The bad ergonomics was my initial thought, too.<p>A laptop is bad enough in that the keyboard and the screen is too close together, forcing you to either tilt your neck forward or fold your elbows to get your hands high enough, but at least you can angle the screen and keyboard independently. To be able to type comfortably, the surface more or less needs to be aligned with your forearm, but on the Ipad, that will put the screen at a 45-degree angle from your eyes.<p>That's <i>in addition</i> to the difficulty of touch-typing on a multitouch surface. I used to have a Fingerworks Touchstream (the <i>original</i> multitouch controller), and it was very difficult to type on without moving your hands slightly and ending up on different keys. (And it even had a row of dots to give you a tactile sensation of where home row was.)  If you were in an even slightly unstable situation -- forget it; totally unusable on a train or bus.<p>I can see how it could be useful for watching videos or passive browsing, but not for any amount of extended typing.