Everyone will love this manga as long as they understand it. The relationship between brother and sister seems too awful, but if you understand their true feelings you won't care about that anymore. The story is quite difficult but I love Kaori Yuki's artwork and I'm sure everyone will love more than a couple of characters there. The plot between heaven and hell is awesome, and I think it has a very deep meaning about the matter of the afterlife and the things that don't are what they seem (like the angels and demons).
I enjoyed it pretty much! n_n Though the only thing I didn't like too much was the ending.... Some things were unfinished.... But well, I loved Kira-sempai and Katou the most! n_n