Ah, Elfen Lied \o/
Lilium, the opening song, is absolutely my favourite anime intro.
Whole series is in high place in my top lists. ^^
But there's some things I didn't like in the series.
1) Nyuu - I go nuts with her...
2) Drawing style. There's something what bothers me in their faces - they look so.. flat, aw.
3) Special episode. Oh my, that did suck, but at least it had some good extra information ^^
Mmm.. that was my second blood-filled anime. The first one was Akira (in fact, it was my first anime movie, and geez, teacher showed it for our class when we were fith graders O_O; My friend got traumatized).