This movie is a weird mix of a teeny-romance, comedy, vampire and a mystery story. - While the most attention is on the mystery story. I am a fan of vampire and mystery stories. So I hoped this movie would suit my taste.
Also I personally find the Japanese Pop culture quite interesting. If I wouldn't, I probably couldn't have sit through the whole movie. It's silly, full of goofs, badly acted and childish. There is very little positive about this movie. The few positive things are: the music and some really nice and creative ideas when it came to the story. Somehow this made it possible for me to be entertained.
Still, this movie is only for fans of the Japanese Pop-Culture. If you are not, it's very unlikely that you will ever come across this movie anyway.