Most readers refer to this novel as an example of dystopia: this is usually a fictional example of a society that, by design, is oppressive, cruel, or destructive. The nation of Gilead came to power because those in charge killed or ousted the people who were running the previous form of government. The new leaders of Gilead (which was previously the United States) have achieved what they wanted (a society where women are subservient to men and made to be reproductive slaves). Because this "new world" represents the goals and desires of those who seized power, to them it is a utopia, or an ideal society.
But most readers' notions of what makes a society function in a heathy way would be at odds with how Gilead is run. Some subtle signs point to difficulty with this new, oppressive system, like food shortages and an apparent reconfiguration of basic commerce. The constant presence of armed guards and surveillance point to a tyrannical situation.
The only way this new leadership can maintain their "utopia" is by using force, violence, torture, and punishment. For those living under this rulership, the world is a dystopia. This calls into question the very notion of how one defines a utopia versus a dystopia: it seems that the definition is in the eyes of the beholder and depends on who is being oppressed and who is in charge.