I don't mind this look. I like that the Ult. Inhuman family were much more inhuman looking than their 616 counterparts. I like that Black Bolt has actual black skin and white glowing tattoos and webbed/winged underarms rather than looking like some random white guy in a suit. The only thing I don't like about Ult. Black Bolt's look is his face. The white mask and tuning fork look silly. I don't mind the dress/skirt/robes. I think it gives him a much more exotic look.
Also, I like Ult. Medusa's look as well. Too bad that such a cool re/design will probably be never seen again. She kinda reminds me of an older version of Delphyne.