I'm a little ashamed to say that I had no idea Maria Anna "Nannerl" Mozart existed prior to this book. I'm not big on classical music, so there really wasn't a way for me to know of her, but I'm nonetheless sad that I had never heard of her before this. I mean, I'd heard of Wolfgang Mozart plenty before, but never her which is terribly sad.
Because this was my first introduction to her, despite the fact that it was fictional, I became very invested in her story. I found myself entranced by this unique and fantastical take on her life, and her relationship with her brother. It is inherently a very fragile thing, given the nature of how society treated her versus her brother, but it was handled very well in my opinion. Truthfully, this style of book was a little unexpected from Marie Lu (who I only know of from her dystopian work), but she clearly knew what she was doing. So far, its my favorite work from her yet!