Arthur Miller created Willy Loman with many flaws. He has deep-seated insecurities, compromised morals, and reversed priorities.
Willy's insecurities stem from being abandoned by his father at a young age. He admits in an imagined conversation with Ben that he has always felt he was "temporary." His constant turning to the specter of Ben for validation shows his insecurity. Because he fears failure so much, he often lies to Linda about his earnings. Biff remarks that Willy "didn't know who he was."
Some of Willy's moral failings are lying, theft, adultery, and misplaced anger. Biff states, "We never told the truth for ten minutes in this house," and viewers note that Willy often reverses his statements within a matter of a few lines. When Willy builds the stoop on their home, he does so with lumber stolen from a nearby construction site. He knows of Biff's stealing basketballs in high school from his employer and does not reprimand Biff, but encourages such behavior. His insecurities lead him to have an affair with a woman while he is on the road; even when Biff finds out, Willy will not confess his infidelity to Linda. She remains in the dark even after his death. His guilt leads him to turn his anger on others rather than deal with his own wrongdoing. Thus he accuses Biff of "spite," which has some truth to it, but he does not resolve the issue by dealing with the harm he has done to Linda and Biff.
Willy's priorities are troubling. His desire to be loved is common to everyone and understandable, but his vision of dying "the death of a salesman" drives him to take short-cuts. He believes the man he wants to emulate achieves greatness just by making himself well-liked, not by hard work. Not only that, he measures success by wealth and esteem rather than by relationships, honor, and helping others. Biff declares in the Requiem, "He had the wrong dreams. All, all, wrong." Willy manifests his twisted priorities by committing suicide—as if the money from an insurance policy could replace a husband and father.
Willy Loman is a low man. He is not a great man with a single tragic flaw, but a human being, who—like many of us—struggles with insecurities, moral failings, and messed-up priorities.
Willy Loman in Arthur Miller's play "Death of a Salesman" is intended as a deeply flawed character. He is not a tragic hero, characterized by greatness and grandeur, but rather a mediocre salesperson, who has in most ways failed to achieve his own aspirations.
The first flaw Willy has is that he is not really a very good husband. Although he does work hard (if not effectively) at his job, and tries to take care of his family, he commits adultery and cannot quite keep up with the bills. As a father, he condones his son's cheating in school, and in emphasizing sociability over good grades, does them a great disservice in terms of preparing his children for the real world of work. Finally, Willy tends not to see reality very clearly, but instead, his perpetual optimism and upbeat fantasies distort his sense of reality.
Despite these flaws, however, there is an almost heroic quality to his final act of suicide, in which he seeks to redeem himself by supporting his family with his life insurance after his death.