when i first started watching elfen lied, i couldnt really get past the third episode because of the incest plotline between kotah and yuka, or nyus "born sexy yesterday" syndrome. nevertheless, i decided to pick it back up and finished it within a day. if you can manage to look past the unnecessary sexuality, even in scenes where the nudity would be considered artistic, i think that you will find a meaningful story. the themes of loss, abuse, and loneliness hit hard, perhaps in a less relatable way than welcome to the nhk, but still extremely prevelant.
i really enjoyed how they handled every single character arc, every one that you are set up to care about comes to a (pretty much) satisfying, and sometimes terribly sad, end. i think that some may think the abrupt and almost cliff hanger like ending of the anime may turn you off from the finale, but i honestly thought it was good-im the type of person who likes an open, speculative ending, even in places where a sequel didnt turn out (or wasnt expected at all). i read that the manga and anime were being worked on around the same time, but the anime was finished first, making the endings not quite line up between the two. i might look into the manga in the future, i dont think its a priority as im not a very big manga reader anyway, but it might be nice to see another version.
i think that my favorite character is nana, i loved her arc, her friendship with mayu, and the end of her relationship with kurama. kurama is also another extremely good character, thinking about him makes my heart hurt. i just wouldnt be able to deal with myself, making the decisions he did. ahhh..... all in all, it started off somewhat stagnant, but regained my interest very quickly. i would probably come back to it in the future, like most animes that i found some sort of meaning in.