Usually when we start a manga the first impression is usually the one we use when we decide if we want to continue reading or not. For me and mushishi that was not the case. I read the first two books and felt completely confused, so I continued reading. after about the 4th book I understood everything and the story started getting interesting (why wouldn't it be? it's about a guy who roams the country in search of scary insect thingys (mushi) and tries to cure people of them, now that's dang interesting). But once I finished the 4th book I noticed a repetitive storyline. He goes to one village, cures it of a "disease" and quickly runs off to save another village. The other repetitive part was that the diseases were all related to people's eyes, hands/feet, and ears. There wasn't anything related to any other part of the body that could provide a change from the basic routine.
The artist really knows how to weird it out. He drew the weirdest things to use for mushi which would add to the effect of mystification. The people that were drawn didn't look anything near inviting to look at, but it added to the effect of the hardships they face with the mushi.
Ginko is really cool in the fact that he is really calm and it sometimes feels like he isn't human because he knows all of this about mushi, and because of the setting and the events. The negative part about the other characters is that compared to Ginko, they are either really superior, or really inferior, there is rarely a good balance between the power characters have over one another and/or the intelligence of the characters.
I enjoyed this manga for books/chapters 5-7. Then I got bored but for some reason kept on reading it. Probably cause I didn't have anything else atm. But there's something about this manga that kinda makes people want to read it till the end, where there's nothing left to read.