In a sense, the tablet format is more than just a software or hardware platform. It's more akin to a new kind of material - one that you can mold at will, through software, into a myriad of distinct widgets.
Don't underestimate hardware. A slightly dodgy software keyboard like the iPad gets rave reviews, where slightly too small netbook keyboards get slated for not being perfect full size keyboards. It's like Johnson's famous comment on female preachers: "Sir, a woman's preaching is like a dog's walking on his hind legs. It is not done well; but you are surprised to find it done at all."
The key of course is that a capacitive touch screen can do lots of different things okay and effectively disappear when not in use, rather than doing one thing really well and sit there as a big hardware lump the rest of the time.