When I began reading this, I knew nothing about this book other than a 3 sentence summary of the plot. As it turns out, to the extent that there is a plot, it is presented in a piece-meal, impressionist sort of way rather than any sort of straight forward narrative. As the title suggests, the book is composed of the monster's notes, not an actual story as such. Instead the book is made up of a series of notes expressing the monster's thoughts about various things, mixed with letters between various members of the Mary Shelley's family, as well as a long section in the middle where the monster imagines correspondence between an Italian leper with no name and Clerval (a character killed by the monster in Shelley's novel) as Clerval translates the Dream of the Red Chamber. In between the main sections of the book there are various interstitial things such as the monster's thoughts on several 20th century cultural figures or ideas, or the monster's attempt to find information on Mary Shelley on the internet in the present day. It is also full of all sorts of references to literature and history that I didn't always understand. Sometimes I looked them up and at other times I just enjoyed the writing without fully understanding all of it. I don't think that understanding every single word, especially those references, was really the point of this book though.
The unconventional way in which this book is structured and composed make it not the easiest read ever, and I could see how it could be a big turn off for a lot of people. However, narrative issues aside, the language is poetic and beautiful. A large focus of the book is the monster's relationships with his creator and with Mary Shelley. It is unsaid, but is sort of implied that those may be the only two relationships he's ever had at all in a couple hundred years of living, but at the very least, those are the two most significant ones. As the monster contemplates what it means to have been created in the way that he was and to have been abandoned by his creator he provides lots of interesting insights into how where he came from defines him and his sense of self worth. As he looks back on Mary Shelley (as well as her step-sister Claire), he reflects on the nature of imperfect friendships, the impossibility of truly knowing someone else's thoughts (or even your own), and the limitations that exists in any relationship. I also thought it was interesting how the monster's thoughts differed between what he thought about his creator, who brought him into the world literally, and what he thought of Mary, who, in fictionalizing him, presented an interpretation of him to the world, in a portrayal that he is not always comfortable with.
The section with Clerval and the Dream of the Red Chamber was longer than it needed to be, and probably worse for people who aren't familiar with the Dream of the Red Chamber. I read it in college (though we called it the Story of the Stone in that class) so was familiar with the characters referenced, and remembered just enough about the story to be able to follow what Clerval was saying about it. For anyone reading this who isn't familiar with that story though, that section was probably very difficult to get through, especially as the letters between Clerval and the leper got more and more tiresome.