I think this manga is incredible, I couldn't let go of the books and read the 18 books in 2 days !...
When you start reading something, you often have an idea of how it will end, but here I was always surprised, until the end I wasn't sure how things would end up.
The subjects are wide and well linked, it is also an interesting thought about the problems we have: environment, war, drug...
But what I liked most were the characters: they are fascinating, complex and imperfect like real human beings. They strugle to go on, make mistakes... nobody is perfect and can always take the best of a situation....
Sometimes characters in manga match an "ideal person" (depending on the characteristics the author wish to develop) too much and loose humanity, but not here.
There is also no cliché with a "bad guy" and a hero.
The manga is also enriched by the number of characters, and even small ones are not neglected. Some say it is more confusing... well it also how life is, even if we interact with a small number of people everyday, a lot more can influence our lives (a litle, or greatly). The manga does not only tells the story of some people, but describe a situation and the number of people makes just it more realistic.
The work done by the manga on this part was great and really nice.
I think this is one of the best manga I ever read !