One of my favourite plays ever written. The story is so simple yet complex. The characters and their characteristics are very relatable and realistic in the most raw simplistic way. Specially the characters of the fathers and sons and their relationship. 
"Salesmen never hit rock bottom" the main character coming from a profession where he was always on the road, making money in good days only to live the end of your life in disappointment, exhaustion and without the money because all he did was spending money on the house, the mortgage, and the family. The loss of identity once you lose your profession is something common I have seen in men. Probably in women too. 

Linda's character too indicate how a lot of women are in patriarchal families. Getting scolded for speaking over, being cheated on or kept in the dark on that detail. She enables her husband unrealistically with her blind loyalty and faith towards him.

The children being pressured to show the parents that they are successful making them feeling pathetic and exhausted in their own time. I love the character development. They are not so different from each other as individuals but all their characters speak much familiarity with family lives and parents.