Not a good beginner's board most likely. Probably stiff with a hell of a lot of camber. Better off finding something more recent on craigslist. The only thing "good" about it is that it is free, so you won't lose any cash if your sister decides that she doesn't like snowboarding. Honestly though, fighting to learn on that board may discourage her.
I don't recognize the graphic, but I doubt it's a collector's item either. Unless you have some attachment to this board, I would consider it junk. Turn it in to a bench or something.