I don't care what /a/ says. Elfen Lied may have sucked balls in several, severe areas, but the gore in the series entertained me in ways the classic, old-school 80's animes never had. I can't describe why, but as a connoisseur of animated violence, it was absolutely thrilling. Animes these days just don’t have the balls to achieve such a beautiful level of violence these days, with a few rare exceptions like Baccano!, and even that wasn’t this extreme. The animation didn't hurt either. Lucy's escape from the Japanese millitary compound is one of the most memorable scenes I've ever witnessed in an anime.
Elfen Lied also delivered tons of sociological symbolism that you don't need to be in the Tuff Dawgs crowd to have been able to see. You can go “lol deep” all you want about the series, but there were symbolic themes of psychology, sociology and philosophy that animes other than Ghost In The Shell fail to even come close to touching on.
Plenty of very forced-feeling moments and unrealistic character-reactions, but aside from that the series was fucking awesome.
Also, ask yourself this: How can you NOT know you're watching an awesome anime when in the first 10 minutes 45 people are dead and somebody pees themselves?