The cover of Malinda Lo's Ash shares a lot about the tone of the book--it is somewhat dark, scary, and sad but also peaceful and magical and beautiful.
It's a Young Adult novel that is is called on the back cover a "retold Cinderella" and "Cinderella, gorgeously reimagined." There is an orphan (Ash), a mean stepmother, magic (here in the form of fairies uniquely rendered somewhat scary and a little bit evil but still magically appealing), an unwed prince, and balls, but to me to compare this to the Disney singing-mice cartoon I grew up with is entirely offbase because of this book's tone and characters.
It is a character-centered story, although the plot is important and the pace is relatively quick. There are details of Ash's vivid dreams, the light in the Wood, the stepsisters' getting dressed for balls, fairy characteristics and clothes, and fairy tales. Yet it still feels very realistic and grounded. Ash is a human girl who is devastated by the loss of her parents but comes to tolerate the life she must live as servant to all that's left of her family. There is also organic-feeling romance.