Elfen Lied is a prime example of an anime that owes it's generally good scores solely to hype. People like it because they are told they will like it. It's a phenomena which, though it occurs in other cases, truly shines through with this anime above all others.
I'll start with Elfen Lied's story. Diclonius, unique human-like entities that have slight abnormalities such as horns, and invisible hands that can shred humans with ease, exist in this world. We are treated to our main character sporting her Diclonius power when she breaks(and then walks) out of a facility. She butchers the whole armed force bent on keeping her in without flinching, while in the buff, though ultimately is injured.
It's not a particularlly bad intro but what you get there is pretty much what you can count on for the remainder of the series. Obscene violence, which isn't bad on it's own right, but the action here basically equates to "my invisible arms are greater than your invisible arms!" When it is Diclonius vs. Diclonious and when it comes to Diclonius vs. humans the word massacre might be too soft. The poor, albeit well animated, violence, coupled with copious amounts of porn and kiddy porn alike just didn't work in this mess, other than appeal to some bizzare fetishes.
The plot is there, I suppose, has a good premise that is wasted(think gantz, and ergo proxy to a degree) on a more mainstream sense numbing route. We have a plethora of cliches to see here: high school boy that is suffering from amnesia and of course has a fairly predictable twist when it comes time to explore his lost memories, superpowered younger girls, flashbacks(not done particularlly well), and scheming individuals trying to claim a main character.
The characters are hit and miss, in the sense all are cliched, and really feel like clones of others in the series, or from other animes. We have a girl with split personalities, a boy with amnesia, and female killing machines, like I touched on before, all of which get old.
The anime serves to desensitize you and feel like you were watching some dirty kiddy snuff porn that doesn't know what it is. And it really doesn't. If it was going for a dark side of people theme, yes it's there, but it does it much worse than any anime I've seen. There's really no one to sympathize with after all, humans are wicked in their treatment of Diclonius, but then again the Diclonius kill(enemies and innocent) with such lack of compassion they sure can't reasonably be sympathized with either.
On one side we have a scene/effect of child rape which I really hate to say, wasn't what was worst in the series.. And on the other, streets being turned to blood soaked riots. The overall result is an extremely watered down version of the darker side of humans niche of anime. Aside from being treated to a nice opening and closing theme that one could fall asleep to, there really isn't much to see here. Yeah the animation is acceptable, but nothing beyond that, and is pretty consistently used to poorly recreate the nude female form, or mass murder, or both. Really this is a lot like Gantz, though Gantz is a little more ridiculous, and at least funny for all it's shortcomings.
Check out the opening song but unless you really want to give it a go, pass on this. I honestly do not know why this is such a raved about anime, it almost makes me worried about my fellow anime fans, but to each man their own!