I'm an old man who reads manga, and I've been doing it for 5 years. I used to find lots of manga that were of interest to people who have been through a substantial portion of their allotted span, but now they're becoming few and far between. I can't complain. I knew going in that manga was pop fiction mostly aimed at very young people, and I learned pretty quickly that it was also very formulaic.
THIS, on the other hand, has none of these drawbacks. Its about learning to survive in primitive surroundings, and, as an extra added attraction, learning to WANT to survive. Over and above that, there's almost NOTHING DUMB in it. The struggles these characters have to go through to keep from starving on the island are all believable, and some are harrowing. The characters themselves are all very distinct, and some of them also actually think about stuff a lot. What I've seen so far of their equally difficult struggle to WANT to survive makes sense, and involves a lot of very interesting thinking and talking.
In short, these drawn characters seem amazingly like real people. This mangaka has created a brand new concept for a story, told it in a fascinating way so far, and elicited a great deal of sympathy in this reader for his conflicted, and conflict-ridden, characters.
It's a real winner. I recommend it to everyone.