Brief overview about mental illness, readers having science/medical background can easily keep the pace while reading. This book would be a bit tough for general readers as it contains many arcane terms from Neuroscience.
Writer still considers homosexuality as mental illness. I believe, based on recent evidence, such consideration should be changed.
Studying mental illness requires significant understanding of psychology, neuroscience, and social psychology. Writer did a good job not delving into the deep of these three areas keeping the understanding issues of general readers.
My personal opinion is epilepsy is not a mental illness, it is rather an aberrant state of nervous system.