There were at least two negative aspects of life in the US during the 1950s.
First, to a certain segment of the youth of the US, the '50s were a stifling time. They felt that they had no way to express their individuality. They felt that their society was excessively materialistic. These "problems" helped lead to the counterculture of the '60s.
Second, US society during that time was oppressive towards various segments of society. Perhaps the two most notable of these segments were women and racial minorities. The '50s were a time when women's roles were diminished and women were being expected more and more to stay home and be housewives. Blacks in the South, meanwhile, were living under conditions of segregation. These facts made this time less than a golden age for those groups.