Kuroshitsuji (aka Black Butler) is a classic revenge story with black magic involved. I won't deny that it's well made and that it has mystery but there are many fillers in the manga (as well as in the anime) that will confuse you. Also, it's one of these stories in which you have to pay attention to otherwise you might find it difficult to understand what's going on on the next chapters. Apart from these negatives, it is enjoyable to read and it will show you a more twisted aspect of revenge. Revenge can drive someone to do insane things and even drive him mad.
Characters & Art: 9/10
The artwork is pretty and the characters' personality as expressive as they should be. The writer did a good job to give the exact amount of seriousness, happiness, evilness etc on every character. I really enjoy the Victorian outfits which don't lack details and the amount of class each character has. The manga may be black and white but personally I didn't find it disturbing just like I did with other manga. Probably because it gives you a goth-like feeling as you are reading it. Moreover, I didn't catch any symbolisms (aka hidden messages) in the manga if you are into this stuff.
I never really understood why some label this manga as shounen. Apart from the red-hair ripper that tries to kiss Sebastian and a couple of other scenes in the manga I don't really see the shounen anywhere. Moreover, if someone wants to watch the anime I would tell them give it a shot but read the manga first. The anime may confuse you due to its lack of conteniousness. Other than that the art and music are really good and the sounds of jazz at the background match excellent the scenes.
It's a good manga (and anime) to read (to watch). If you are into classy, goth-like stories then you'll enjoy this one.It's not perfect, but it's not bad either. I believe it could get higher rating if it didn;t have some imperfections. Still, not a bad work.