Take it from me-- it's realistic
Even though I (fortunately) neither suffer from depression as severe as Esther's nor have to deal with the oppressiveness of the 1950s, I found her thought patterns very familiar as I have just started therapy for my depression. Many complain about how her thoughts seem disjointed, but her writing style seemed to follow my own thought patterns, something that fuels the frustration of the disease even more. The book made me feel very fortunate to live in the 1990s, when sympathetic psychologists don't dismiss irrational feelings, and pills keep me from having to endure shock treatments or other such practices.