I think the iWork apps are going to be the dark horse, and will end up becoming the "killer apps."
On another note, the big difference I've seen with the iPad (iPhone OS) compared to other tablet is the flourishes on UI elements.
With the iPad the UI elements, animations and transitions seem natural. Things move where they're supposed to, they look amazing yet functional, and don't interfere with what you're doing.
It seems that in trying to differentiate...