Indeed she is. One of my favorite Queen's Blade characters. She doesn't seem as popular as some of the others, but I find her rather intriguing and I like her design.
Ntx, Airi and Alleyne are easily the most attractive girls in the series. Airi gets more attention because of meido appeal, and I don't see why not many people like Nyx. Maybe because of her psycho nature in the books, and loser status in the manga...