The society in this book is a utopia

No, it's actually a dystopia.

The society Lowry depicts in The Giver is a utopian society—a perfect world as envisioned by its creators. It has eliminated fear, pain, hunger, illness, conflict, and hatred—all things that most of us would like to eliminate in our own society. But in order to maintain the peace and order of their society, the citizens of the community in The Giver have to submit to strict rules governing their behavior, their relationships, and even their language. Individual freedom and human passions add a chaotic element to society, and in The Giver even the memory of freedom and passion, along with the pain and conflict that human choice and emotion often cause, must be suppressed. In effect, the inhabitants of the society, though they are happy and peaceful, also lack the basic freedoms and pleasures that our own society values.

In this way, The Giver is part of the tradition of dystopian novels written in English, including George Orwell’s 1984 and Aldous Huxley’s Brave New World. In these novels, societies that might seem to be perfect because all the inhabitants are well fed or healthy or seemingly happy are revealed to be profoundly flawed because they limit the intellectual or emotional freedom of the individual. 1984 and Brave New World both feature characters who awaken to the richness of experience possible outside the confines of the society, but they are either destroyed by the society or reassimilated before they can make any significant changes. The books function as warnings to the reader: do not let this happen to your society.

The message of The Giver is slightly more optimistic: by the end of the novel, we believe that Jonas has taken a major step toward awakening his community to the rich possibilities of life. The novel is also slightly less realistic: although the technological advances that allow the community to function are scientifically feasible, the relationship between Jonas and the Giver has magical overtones. But Lowry’s dystopian society shares many aspects with those of 1984 and Brave New World: the dissolution of close family connections and loyalty; the regulation or repression of sexuality; the regulation of careers, marriages, and reproduction; the subjugation of the individual to the community; and constant government monitoring of individual behavior.

It may look like a utopia but really it is the opposite. People seem happy, depending on who you were, but in reality their existence is quite child-like and immature. People are controlled and their "utopia" is hence superficial and rather meaningless. When there is no pain, one can't know pleasure. The society thus becomes dystopian rather than utopian.