An imperfect, but nonetheless interesting whistle-stop tour of 'modern' psychology.
One major problem that other reviewers have pointed out is that Benjamin totally ignores anybody outside of Europe and the Anglosphere, so this is a 'Western' history of psychology. Also, Benjamin appears a little uncritical of certain perverse aspects of psychology (race science, corporate psychology, sex difference psychology etc). These for him are not evidence of the dangers of psychology and it's contamination by the state, bad actors or the ruling class, but mere historical incidents, reported neutrally.
However, for a quick bite-size summary of psychology for an undergraduate who hasn't heard of Emil Kraeplin, Wilhelm Wundt or Otto Klineberg, it's a useful volume to get started. Perhaps follow this up with Fancher's 'Pioneers of Psychology', as it is a much cheaper volume, more readily available, and that particular volume appears to have influenced most of what Benjamin writes in this text.