I was at first hesitant to read Mercy, since I've been underwhelmed by most recent books about angels, but Mercy's premise seemed unique. The whole angel theme isn't very prominent in the book - the plot mainly revolves around the mystery disappearance of Ryan's sister. If the blurb didn't say she was an angel, I wouldn't have known. All we learn through the story is what Mercy can do, not what she is. Which makes sense, considering Mercy herself wouldn't even remember.
I liked Mercy as a character. Her personality seemed appropriate given her predicament. She's hardened, doesn't care what people think of her, and seems older and more mature than the teenagers around her. She feels genuinely sympathetic for Carmen, the host, and keeps in consideration the fact that she'll have to resume the life Mercy leaves her with. I liked how Mercy felt separate from Carmen, always talking about Carmen as a different person.
The mystery surrounding Ryan's sister's (Lauren's) disappearance was well-written, and Ryan and Mercy had to follow more than one lead before discovering who was behind it. I didn't understand Ryan's sudden trust in Mercy, allowing her so quickly to help him, but I liked the pair together.
However, some of the secondary characters felt cliched (see Carmen's jealous frenemy from choir, Tiffany), and the ending felt rushed. It cleared up the main problem - finding Lauren - but didn't address anything about Luc or the other angels.
I look forward to further books in this series, Exile and Muse, in hope that they'll focus on the more paranormal side of the series. I give Mercy a 3 out of 5.
P.S. The Australian covers for this series are gorgeous:
I read this book for the Aussie YA Reading Challenge.