The Great Brain is wonderfully written, sometimes hilariously funny, and gives a well-seasoned look at life in rural Utah in the 1890's. I thoroughly enjoyed reading it.
It does, however, have numerous cautionary aspects for parents to consider for children. Tom is greedy, and he takes advantage of others, including his little brother, in unethical ways. He does reform in the end, is not malicious, and one gets the feeling that he is a good boy at the core. Most parents would not, however, want their children to mimic many of Tom's actions.
Some situations might be intense for young readers. The death of a Jewish man from malnutrition was hard for this adult to read, and the chapter in which two boys are presumed hopelessly lost in a cave might be unsettling. The chapter in which J.D. attempts to help Andy kill himself was quite disturbing. I knew this was based on a true story, and I kept thinking that J.D. could have easily actually killed his friend. Parents will also want to consider whether they want their children reading about ways in which children might commit suicide.
Overall, this is a satisfying book. Parents are wise and revered, even if occasionally left in the dark about their children's antics. Townspeople are involved in each other's lives, even if they can be occasionally annoying in doing so. Some scenes, like the public unveiling of the town's first water closet (toilet) are very funny, as is the view of Tom through his adoring and naive little brother's eyes. It is a book our family enjoyed, but may not be for everyone.