I first learned about Genie's story while doing research for a college thesis. I had personal experience working with children who had been victims of severe neglect, and was writing a paper about their difficulties with language acquisition.
This book struck me to the core. Not only is the subject explored so poignant, so heart-wrenching, but it's written with an expert hand. It gives humanity and dignity to a character who was robbed of her own. It keeps you deeply engaged. The book says with you - it would be impossible to read it and not spend a long time afterward thinking about it.