Not seen, I didn't even know there was an anime of, however I have read the series twice though.
It's one of those series I read completely and then don't bother with it for months and then read it again completely, this time with the new chapters.
I've read some of it and seen some of the anime. It is an all right vampire story. There is a weird pedophile vibe I get from it though. The main character is very old, but has the body of an pre-pubescent girl. There's nudity too. I feel a little icky watching/reading it.