I almost DNFed this book, but then there was a hook that got me. I'm glad I finished! There were parts of this that really creeped me out, but also parts that made me laugh. Mary sometimes felt relatable and her inner-monolgue was sometimes funny, and other times super depressing and hard to read. 
But please, don't make the same mistake as me. Do not read the afterword.
And DEFINITELY check content warnings!