To me this Microsoft tablet is another iteration of the slate TabletPCs that has been available since 2003. (Actually earlier than that, as I recall a Fujitsu slate that is Win98 powered, but WinXP gained TabletPC support in ca. 2003.)
As someone who has owned a slate TabletPC since 2004, my advise is to brace for disappointment, though it is no fault of Microsoft. Microsoft has been steadily improving TabletPC support since XP, but the vast majority of developers did not want to take the risk. So you will be stuck using an onscreen or external keyboard as input most of time. On the rare occasion you come across an ink-enabled application, it is a real joy.