For me it's 3.75 stars, I liked the setting and the characters a lot, but I felt like it was very predictable, and a lot of things were happening in the ending, and it felt rushed. There were moments in the last few chapters when I didn't know what was happening.
So glad it had a somewhat happy ending, I was doubting it was going to be a sad one.
Also, I wish the author did something more visible to make it clear when Greta is seeing a vision of the past, and when it's the present. For me, it was a bit confusing at times.