Good story in the prequel style
On a scale from "Full Moon" to "New Moon," I'd rate this a "Gibbous." This fiction was written before Season 2 so the canon is a little clunky, but it helps with the characterization of Luna. The writing is generally okay, slipping into some really good lines here and there. The story doesn't really explain all that much, like where the Elements of Harmony come from, but that's not a dealbreaker. If you can get into it, it's a passionate and heartbreaking tragedy.