Meh, I've read the manga up to the latest chapter translated, and most of the anime. I really do not see whats so good about it. The dialogue is rather awful and the storyline isn't even that great. It is one of the most intense series I've followed though. The ending in the manga is much more concluding and about a thousand times more depressing.

Won't get into details why or how, but Kouta and Lucy end up at the top of a building and Kouta has been shot. From the shock of it, Lucy pretty much shouts that she is going to destroy the world. About a second later she releases this aura of power and her hand melts off. (the more power she uses, the more she melts) Although Kouta is still alive, he can't take much more, so Lucy devotes the rest of her power to protecting Kouta from the incoming army that has detected Lucy. As she protects Kouta she sings Elfen Lied (some German opera-like song) even though she continually melts. Eventually, she is no more than a body and a head. While in this state, Kouta wakes up, and Lucy wants him to shoot her.
(That was what happened at the end of the latest chapter (103 of 107) so its pretty close to the ending)

In other words: