Yeah, pretty much what they said:
I've seen a few episodes of Death Note. My sister loves this anime, for some bizarre reason. I, personally, find it disturbing in the extreme. The entire show basically revolves around the idea of an extremely intelligent teenager finding a book that allows him to kill anyone, anywhere, as long as he knows the name and face of his victim.
As you can imagine, that leads to some seriously effed-up behaviour, as the, er, "protagonist", Light Yagami, fancies himself to be the "god of the new world" and sets about moudling a world in his very twisted image.
Maybe it's because I used to be an atheist, or maybe it's because I know a little something about irrational teenagers- having essentially watched one growing up before my eyes. But it's probably fair to say that putting that kind of power into the hands of a clinical psychopath isn't exactly a brilliant idea.