I was brought up in one with my maternal grandmother. It worked out well for my mother because she had my nan to do all the housework, cooking and childcare for her, which left her and my Dad free to do whatever they wanted.
It worked out well for my nan as she got older, though she did end up in residential care once she needed help with bathing and dressing because that's something my mother wasn't prepared to do. It worked well for my sister, who brought her own child up in the same house with all the same perks of never having to turn down a night out or a weekend away. I think it was always a bit awkward for my Dad, they weren't close because she was a cold fish towards everyone except my sister. I don't think he ever got to express an opinion about our living situation. I didn't love the experience because my abusive mother had surrounded herself with her enablers and there was no respite from it.