No one's going to write their next novel in Graffiti; it's just not practical. But for jotting down short memos and notes, it's quite good. And if you don't need to export things as ASCII text, programs like Diddlebug let you draw small notes and images on-screen.
If voice control ever really gets going, that will probably be the best method of all. But it takes more horsepower than the current Palm CPUs can deliver (and maybe more than the WinCE devices); there will be a tradeoff between utility and battery life for a while.