I was pretty happy to find that my school library had a copy of this (their selection of manga/graphic novels is a bit odd, I would love to know how they choose what to get) not only since I've wanted to read it for a while but since I've heard a lot of good things about it. And I can say now that those good things were well deserved, although the negative points other reviewers have brought up turned out to be valid too.
Children of the Sea volume 1 by Daisuke Igarashi
The Good: The story set up here is a bit different from normal, instead of launching into a grand saving the world plot or a slice of life story that slowly builds up to an overall theme, Children of the Sea introduces what appear to be it's overall conflicts early on but then lets them sit there, mellowing, as the characters slowly piece together what is going on. It's detailed enough to keep you interested yet the tone sets the mood for a lazy afternoon or reading and the slowed down pace really makes you enjoy the art even more.
The Bad: This is a really odd mix of magical realism and slice of life fiction so not everyone is going to like it. You simply have to accept that Sora and Umi were somehow raised by dugongs and that Japan's children services aren't playing the slightest bit of attention to them, which I remember as a cliche I hated back in my MG reading years. The pacing here is also very slow, we know something is happening but there were barely any vague hints on the who/what/where/when/why/how. Again, both of those depend on the reader's taste but I can see them really driving away a lot of people. My bigger complaint with the story is that it's interesting while you read it but after you sit and think about it awhile you end up going "did much happen in that at all?"
The Art: The art here is of the pen and ink variety (which I love more than Japan's current trend of screentone abuse, oddly enough I only see that in manga, not in Western comics or webcomics) and I liked it quite a bit. You can see all the work and all the detail that went into every page and there were a number of gorgeous two page spreads as well. It's wonderfully different to look at and I love that Viz included the color pictures and printed it bigger as well.
I really did like this book but I want to read the next few volumes NOW before I forget the details or about the series itself. I believe that Viz has a few chapters of it up on their website (Sigikki.com) but I found the first volume at my library. Actually, if I knew of a library that was trying to start up a manga section for teens I would suggest a number of Viz Signature line (like Ooku:The Inner Chamber, Pluto: UrasawaxTezuka, and Children of the Sea) since they are really good examples of how manga can be aimed at an older, but not necessarily adult, audience and can contain more mature themes where mature doesn't always mean sex, drugs, and rock and roll.