I'm personally into slimmer women, but that's not really what we're discussing here. I think the dress suits her well, and i'm not like 'oh she shouldn't be wearing a dress that size'. It makes her look good, and I would imagine if I was into women that size, I'd be thinking damn, because it's flattering.
I don't like that dress on her, but not because she's plus-sized. I really don't like the color for her. I think she'd look better in something that played up her skin ton or at least her hair and eyes.
Eh. Honestly, I don't think it look's good on anyone. Skinny or larger. It's not a very " forgiving " dress, so if you have a lot of lumps and bumps ( which there's nothing wrong with that ) but don't want them showing, it's going to be very hard to cover them in a dress like this.