I will be refering to the English Dub of Elfen Lied.
There also will be spoilers, I'll make a notice before anything is mentioned, but keep in mind that this is a review and there will be minor information that may reveal subplots in the anime.
First thing people get out of Elfen Lied would be blood and breasts. I get it, the blood is too much, and the breasts are overused. That's maybe the only flaw in the animation, however its a part of the art to help send a message across.
The show has 2 characters, where the man, Kouta, ends up being quite significant. Nyu is a third character... See full review