It's the second title of this graphic novel that made it a must read for me: The Mermaid in the Hudson. I love mermaid books, especially when the author is able to balance their alluring and dangerous qualities. Siegel certainly manages that, and more.
The mermaid here is the creature of folklore, with a siren's voice. There are places where this mermaid (called South) diverges from what I know of general mermaid folklore, but that all comes much later. There is a mystery here, with enough glimpses given that the reader can guess the generalities, but not the specifics. The characters are, for the most part, fairly realistic versions of people, especially the main character.
The art is unusual, for a graphic novel. Siegel chose to use charcoals, which gives the scenes a lovely, smokey, dreamlike quality. This works best in the scenic panels. The character work, on the other hand, is inconsistent. Some characters are fairly realistic, others are slightly stylized, and others are complete caricatures. The main character has been reduced to the barest sketch of a face, just a nose and two empty eyes. I wouldn't mind the lack of detail, if it were a consistent style. But the art is beautiful far more often than not (just look at the cover).