I loved this!
The first three parts in the series focus on Sophie, and seeing the world through Gabrielle's view in this novella was really nice and different. While they face some (/many) of the same challenges, they have quite a different approach and background in regards to dealing with them, which is nice to see.
I liked the non-linear storytelling and the fact that we saw Gabrielle during multiple stages of her life. Even though the book is quite short, this gave a broad and indepth view of who she is as a person, without it ever feeling like an infodump.

(I also may have made some celebratory noises out loud when I saw the announcement of a part 4 of this series :D )