I guess a lot of it is down to personal experience and preference. When we went to get a Yorkie a lot of people told me he'd been yapping all the time! But he never yapped at all.
My baby would bark at certain things like the postman, people coming home and strangers, they're quite protective, but he never just yapped or whined for no reason.
I also found that he was great with kids and was never agressive when we had visitors. At first he'd be a little weary but once he saw that we were friends with the visitors then he'd calm down too.
Our Bubbles also stayed quite small. He was what they call a 'toy' Yorkie and was always neat enough to curl up on our laps. My younger cousin adored him because he was small enough to sit next to her unlike her larger dog.
I think Yorkie's make great family pets, they're very loyal and loving.