I am new to this site, but I just came across this discussion and it reminded me of how much I loved this book. I first read it when I was in high school, and as many have said here, it stuck with me. I have read it again as an adult, and it remains as intriguing and gripping as it did when I was younger.
I think the reader is drawn in to the emotional side of the characters, not only Charlie, but the others who interact with him as well. I think as human beings, we have all experienced or at the very least, witnessed some of the things that are addressed in this book. I think it would be a good addition to high school reading classes or freshman college classes, not only for the academic literature part of it, but also for the compassion for humanity it teaches.