Don't mean to be negative here, but to me this gown is just slightly "off". Especially love the black (velvet?) trim, the shape of the neckline and the whole shape/line of it, but the main fabric to my eye looks a little... lingerie-ish.
I just find most of her attire things that I would "like to love", but it doesn't quite get there. Here is a similar "lace effect" dress, if that's what you'd call it, which I think is just....better. This is Queen Max, who is just stunning when she gets it right! If this photo, in my opinion she got it right, and more. (See thumbnail.) I do think black lace can be a challenge, to keep it from looking like lingerie.