In my opinion this should be at least in top 10(of all times) manga.The story is incredible and the characters are so perfectly made ^^.
I've read a lot of mangas most of them were comedy/romance (it depended on my mood),but this was the greatest i can't explain the feelings that i've witnessed reading it, the moments of love and drama really made my cry(and i'm a guy -__-).
A great manga is not about how much popular other say it is,you just have to read it and you will know for sure because slowly you will start to be addicted to it and you will want it to continue for ever.. Mainly your read something because you like it because you learn something that might help you in life/make you stronger or even make you a better person.
Overall i've said to much(to many unnecesarry things). Remember NEVER give up,love ,friends&family can't be brought with money(like Domyouji that had everything except love and his family) and if you think that i'm pathetic(some scenes made me cry) than try to read it and see for yourself were are you really standing in life.Enjoy ^^