This picture is what could be defined "beauty performed through simplicity". A masterpiece IMHO.
So far, with everything I've seen representing Remilia, it's by far one of the most accurate pictures that define who she is. It relays very well the subtle mix of power, beauty, charm, undying youth, adult and cute girl all at the same time. In other words: what a vampire is supposed to be.
No need for flashy colors, fancy poses, neither bratifying nor adultification, no "I am the king", no exaggerately long nails. Just Remilia, drawn with a very smooth pencil.