Yes, the blurb manages to describe what is typically considered to be a SF novel without ever once uttering the words "science fiction" or even "speculative fiction." Indubitably, there will be those who will examine the setting and conclude that the narrative is flawed because it resembles this-or-that previous SF setting without taking into account recent trends in the field. On Such a Full Sea certainly is a high-profile enough book that there will likely be some debates in the coming weeks and months on its merits as a SF novel and why certain other reading communities possibly will not accept it as such. Invariably, this happens with any well-known book that appropriates certain tropes in order to tell a different sort of narrative.
Based on the first third of On Such a Full Sea that I have read, the setting is subordinate to two things: a mystery surrounding a B-Mor resident's disappearance and the character development of the woman who leaves the safety of her enclave to search for him. In similar tales written by those who more closely align themselves as being SF authors, it is the setting that take precedence over the characters. But in Lee's novel, what is interesting is the imagined history of the enclave and how that history (of a second wave of Chinese workers brought en masse into the US as a cheaper form of labor) shapes the narrative. Lee, it appears, is more interested in power dynamics, between those who seek to keep others in their own and the deleterious effects of hegemonic influence.
While there are certainly many SF authors who do explore this, often fairly well, in their narratives (Kim Stanley Robinson comes to mind), Lee's story strikes me more as one that is more concerned with the interactions of individuals within a society than on analyzing societal mores. It is a promising novel so far, with some wonderful prose and characterization, and it certainly may appeal to others who do enjoy SF (not to mention those who might read this as not-quite-SF-so-I'll-try-it) stories that focus on not just the effects of human actions but also on the intersections of society, culture, and individual desires and dreams. I just hope there won't be as much nittering and nattering taking place as what I saw after Cormac McCarthy's The Road came out. Sometimes, no matter their dressing or marketing, some narratives naturally appeal to multiple audiences and I suspect that On Such a Full Sea may prove to be such a novel, if the final two-thirds lives up to the promise of the first 100 pages or so.