So this is one of the few YA books out there with a trans character and it naturally piqued my interest. I enjoyed it, but it's not without flaws. I found both Regan and Luna to be incredibly selfish at times and none of the characters were very likable, probably owing to the lack of development. Luna didn't seem authentic to me, either. She was written more as a caricature or stereotype, the author's impression of how transgendered women should be. Similarly, Regan's narrative voice rang false to me. I understand why Peters decided to tell the story from her POV: she's like the everyman character, who can learn about transitioning along with the reader... she questions Luna's trans terminology ("What's S.R.S.?") and teases out explanations for her feelings and actions. It was just a little too transparent for me.
The story itself follows a very predictable path and there's nothing that unique about it, though I did like the use of flashbacks.
The very simple writing style and educational aspects would make me push this to the younger side of YA, maybe even Middle Grade. While I didn't personally love it that much, I would definitely recommend this and hope it reaches a wide audience. There have been more and more novels in the past 10 years or so featuring LGBTQ youth as protagonists, and that is a Good Thing. This may not be the best one, but it's still important.
I totally cried at the end, too.