Hmmmm....it's messed up, will probably scar you for life if you watch it....so Im going with it depends on taste...? I wouldn't recommend it to people I like thoughIt's a slice of life anime that turns ugly.
I would recommend Higurashi no Naku Koro Ni though. But be prepared, it's more bloody than Elfen lied(which is awesome btw)
I love HSOTD and started reading it as soon as it was on stoptazmo. Pity its not regularly updated. Its a awesome series that leaves you wanting more.