Lois Lowry's book about a futuristic world where inhabitants are anesthetized for most of their lives is one of the most commonly banned young adult books. Dystopian novels don't always get a warm reception after all (sorry 1984) and one geared toward children has apparently been called "inappropriate for age group"- a very common assertion.
Personally, I read that book when I was about 12 and I loved it. Still, it is probably one of the most significant reading experiences of my life. It illustrates the importance of individuality and emotion, that sometimes unpleasant things in our life must be there- if we weren't able to feel the unpleasant, we would also miss out on all the beauty and all that gives life depth.
I would recommend this to any young adult reader. Expanding a child's awareness and making them more conscious is not a bad thing, making them thoughful will help them grow into better adults.
When I searched it to check the book's release date (1993), I discovered that there are two companion novels- Gathering Blue and Messenger. I probably never heard of them because they were released more recently, 2000 and 2004 respectively.