This is a middle-school level book, if not elementary. The plot is absolutely straightforward, with only one (rather formulaic) plot twist of note. The royal priests divine that the next queen will come from a tiny, illiterate mountain village. Therefore, all girls of applicable age must attend a newly-formed academy for a year to become acceptable candidates.
Our heroine has the Disney-plot/curse all over her. She is the youngest of two girls; her mother died right after her birth; she is the smallest girl of her age group; and she is left out of things by her loving-but-distant father. She is pretty, smart, talented, and outgoing. She likes a boy in the village who is also a little different and more gifted than the rest.
You can probably fill in the plot from here.
I recommend it to anyone who would like to see what happens when an old-fashioned governess takes on an entire village-worth of Heidi. Alternatively, I recommend it to people who liked Heidi, thought The Selection was missing something, and don't mind a Sound of Music soundtrack.