Snowman is a guy who lives in a tree.
His only clothing is a sheet that he wraps around himself and he lives off of energy bars, canned meat, and the occasional fish.
The world Snowman grew up in was taken over by scientists who biologically-engineered or modified everything they could get their hands on - food, animals, babies.
Eventually, one scientist created a whole new race of humans who had all of the undesirable human behavior programmed out of them. These new humans, called the Children of Crake, are pretty naive about the dangers in the world and it is Snowman's job to protect them. Snowman is also one of few surviving humans left in the world.
The book seems to go nowhere at first, with the backstory unfolding slowly as Snowman hallucinates, ruminates, and dreams up in his tree. He finally decides that he needs to go take a walk back into town to stock up on another energy bar or two. He makes it back alive just in time to discover that the Crakers have encountered other humans. Annoyed, Snowman goes off with his spray gun to take care of them.
This book was just interesting enough for me to read it through to the end. Mostly, it was depressing and crude and I was glad when it was over, even though the ending was weak.
The Children of Crake are on the same path that the humans before them went down.
So what was the point?