This biography is to Mary Wollstonecraft and her daughter Mary Shelley what The Brontës by Juliet Barker is to Charlotte, Emily, and Anne Brontë. Meaning: if they're is one book you want to read on the two Marys, this is the one.
One unique thing about the book was the alternate chapters. Instead of talking about both women in a chapter, Gordon instead would dedicate one chapter to each woman at a period in her life. We literally go back and forth between the two.
Wollstonecraft, unfortunately, did not have as long a life as her daughter. Because of this we 'spend more time' with her in order for the chapters to remain even. We're more focused on certain periods of her life, whilst with Mary Shelley it's more spread out.
While a tome, it was very readable. I never felt bored or felt that there was a bunch of information being thrown at me. A great biography about two incredible and revolutionary women.