I've seen both the serie and movie a while ago and I don't consider it that bad of a show but from what I have seen on the internet, it is not rated really good. It seems that it's not as good as its counterpart Blood+ either.
As for myself, from what I recall of the show, it was passable but unless my memory plays tricks with me, the ending is rather frustrating as we don't get much of an answer about why the bad guy does what he does. So it seems rather meaningless and unsatisfying to me.
I found the visuals and some of the monsters interesting but I can't really say if you or your cousin would like it. You can probably find a video on Youtube of someone (that remembers more about it than me) reviewing it to see if it fits your liking/expectations.