Although it is, of course, an example of science fiction, The Dispossessed has many of the qualities of a romantic novel—it is evocative, atmospheric, and dramatic—while retaining a careful economy of language and never becoming overwrought. By keeping its narration formal and expository, the novel retains an authoritative quality that enables it to capture a certain mood using decisive language. Moreover, the authoritative narration contrasts with the more imaginative, expressive dialogue, making each effect seem all the more noticeable.
To add to this, Shevek himself is prone to passionate moods, with soaring peaks of joy and plunging periods of sorrow and despair. He experiences the world in a profound way and is often at the behest of his emotions. Because the novel follows Shevek, the overall narrative mood tends to reflect his current state of mind or emotional landscape, providing readers with a window of sorts into what it's like for him to move through the world.
What's more, the novel—on the whole—has a solemn quality to it, even in its more lighthearted moments. This solemn quality reflects its serious engagement with philosophical questions of how societies are structured and what effects different structures actually have on individual lives.