Up to 78.2% of the time, reading enjoyment can be predicted by how closely a book adheres to expectations. It's been proven by science.
Most of us select books to read based on our mood. So if you picked up On Such a Full Sea, for example, noted that it was classified as science fiction and expected it to be about starships and space exploration, you would be sorely disappointed.
If, however, you were really in the mood for a literary adventure/romance with a compelling lead character, it would ring all your bells.
The sci-fi label isn't totally unfounded. Lee's story is set in a weird, futuristic-but-depressed version of the United States. His main character, Fan, lives in a settlement called B-Mor, situated in what was once Baltimore, Maryland. The people in the settlements, Fan included, work to make food and goods for those who live in the Charters, wealthy enclaves kept separate from the teeming masses. I hesitate to make the obvious Hunger Games connection here, because the book actually bears little resemblance to the YA trilogy, but the predatory relationship between the capital and the districts certainly came to my mind as I read.
When Fan's love, Reg, disappears suddenly from B-Mor, Fan does the unthinkable: she leaves the settlement to try to find him. The story of her journey is narrated by a cloud of witnesses, the people she left behind in her hometown. The first-person plural narration, always a risky choice, didn't really add much for me, though I'll admit it stressed the collective spirit of the community and highlighted Fan's outlier status. She is special—not because she's particularly savvy or skilled, though she shows herself to be quite shrewd—but because she's willing to leave the sanctuary of home in hopes of finding Reg. It seems that kind of powerful, sacrificial love has been bred out of most of the population in Lee's imagined future America.
Lee makes some larger points in the book about race and environmental degradation, but what I found most compelling personally was Fan and her mission. Since we never get the story directly from her perspective, she remains enigmatic, her epic journey more legend than fact. She's simultaneously an everyman (everywoman?) and a mythic figure. And there's something really satisfying about a strong, capable woman venturing out on a quest to save her man—talk about a refreshing reversal of the damsel in distress archetype!
Bottom line: If you're in the mood for science fiction, this probably isn't the sci-fi book for you. But if you like characters in love who sacrifice everything to be together, it might be your cup of tea.