Mantel writes about her working-class childhood in Hadfield, Derbyshire and then about the illness that blighted her adult life. When she's being a child she sees things as innocently and acutely as Dickens did in the early chapters of David Copperfield; when she writes about her illness and the culpable uselessness of the medical profession she is very, very angry.
If you have a taste for Mantel's fiction this book will tell you something about the roots of her art.