Dorohedoro is in one word unique.
One might also describe it as weird, bizarre, eery or simply creepy.
Magic is really nothing new to be used as theme in manga, but Dorohedoro turns even this highly used concept and manages to deform it to something you've never seen in any other work. I don't want to go into details now, because I'd have to spoil parts of the story, so I'll only say this:
Magic in Dorohedoro is not shining nor sparkling, but rather the complete opposite and that is what makes it so interesting to me.
The art on this series most would describe as flat out bad, that was also one of the reasons I initially dropped this manga, because this unique style of art certainly ain't for everyone.
Yet, it fits the overall mood and setting of Dorohedoro, so after you read some chapters and understand what this series is about you wouldn't want it drawn any different.
Another strong point of the series. The protagonist is as unique as one can get: A human with a reptile's head, the heroine is someone who can fight on her own, the side-characters are more than simply that, they all have a story of their own in this work. The antagonists are not some straight out bad guys you'll come to hate, but rather just like the "good guys" but due to certain circumstances they're doing things that make them look bad. As a reader you can sympathize with them just as much as you can with the protagonist or really any other "good" character in Dorohedoro.
Given all the points above I greatly enjoyed this manga, despite, or maybe because of its weirdness. I mean, weird doesn't automatically equal bad, right?
An objective 9/10, but in my opinion Dorohedoro deserves a bonus point (+1) for it's originality and uniqueness so 9+1=10.