I'm surprised no one else has seen this fascinating Anime/Manga. The pattern you see on the clothes/backgrounds are actually photoshop textures. It's amazing what you can do with Photoshop, ne?
In any case, it's not entirely faithful to the book. Gankutsuou, which literally tanslates to "King of the Cave", is a demon that Edmond Dantes found while he was in prison. In exchange for his freedom and good fortune, the demon would control a part of him. That's why Dantes is blue and Vampirish looking.
Also, they combined two characters to make Beppo. Originally, Albert had first been seduced by a woman, then a man switched places when Albert went to meet her at night. Also, Luigi let Albert go in the book because the Count had saved his life and Luigi had sworn to respect him and his own (meaning his friends). In Gankutsuou, to get Albert back, Dantes basically made Luigi shit himself.
There's a lot of other changes from the book, like Haydee being his traveling companion from Eastern Space rather than a slave from Greece; and Albert's fiance in the book was just lazy as hell rather than an energetic tart as she's portrayed in Gankutsuou.
It's definitely worth a watch. The imagery is amazing, and the story has an altogether different ending from the book.