On the plus side, this novel paints a more complex portrait where Juana comes across as an assertive woman in a time when women (even queens) were supposed to be mostly compliant and take direction from the males around them. Juana is a victim of politics where rival rulers (her father, husband, and son) all plot to keep power in their own hands.
And as the reader, you aren’t really sure how much she’s mad and how much she’s simply insistent. That part is interesting to consider.
On the negative side, the book is not very well written. There’s little emotion and, with the exception of Juana, the characters are mostly one or two-dimensional.
The writer sometimes ends chapters where much is left hanging — and then picks up the next chapter, where years have passed with a page turn. The result felt disjointed to me.