I could talk about the story, the characters, even the art, but I guess my colleagues here could sum up pretty well everything I could say. One thing that I'd like to point out - and it is what really draw me to the manga - is the amount of subjects that they bring (I, myself, am re-reading the manga and I am writing down all those mentions). Do you wanna know about art? There's an arc about Van Gogh and Venus de Milo (and if you are willing to search everything they say you will have to search about Cezanne, Gaguin...). You want to know about classical music? Mozart is mentioned and the legendary violin made by Stradivarius (which is not so amazing after some researched I've done about it). There are biblical mentions, witch hunt, there is seriously too much to know about here, if you are a curious person, if you like to learn about the most random things (and you are willing to search further everything that you read in the manga) I'd recommend you to read it.