I watched the anime because I promised a friend I would and after the first 5 minutes I was about to break the promise. However, I continued to watch it and at a point I realised that I wasn't watching it just for the sake of a promise anymore, but because I had really grown to like it.
There is a lot of blood, that's true, but it's the story that matters. Lucy is not a cold blooded series killer. I believe that Nyuu shows her true nature: she's caring, capable of feeling love and hates to see the people she loves sad (
think of the episode when she broke the shell because it made Kouta sad, or when she cut her hair to look like his little sister and tell him she forgives him
- a cold blooded person wouldn't do such things).