Though this story is very memorable, it is not happy at all, in fact, Yuri's life is almost a non-stop story of misery. It definitely makes you think, though.
I would recommend it to older kids, because, although it seems simple enough - an adventure story about a boy surviving in a harsh environment, it's not.
I don't really like the person Yuri has become, a harsh, cruel person, although I suppose, what could you expect? Being sent to do hard labour in a harsh environment where death is routine when you are 12 must be a tough experience. There he learns how to squash all sense of compassion and pity in favour of survival.
This novel deals with those troubling questions about how humans can be such monsters in the name of making the world a better place. "Faith," one prisoner speculates, "A cause behind you... they're blinded by it. Fortified by it. So fortified that what they do seems good and worthy even if, done for any other purpose, those very same things would seem shocking, even to them."
I think Yuri is swaying dangerously close to that "faith" idea near the end. He is so set on getting people to join his cause to defeat the evil tyrant, that he thinks, for example: "...if those too stupid to understand the aim in view had to be whipped int seeing that they'd been beaten for too long, then whipped they must be."
All in all, this book is memorable, if not happy, and I'd recommend it to those who would like a deep read.