I genuinely do not see any fault with this book.
Octavia E Butler managed to put on paper the intense complexity of our emotions, how easily we become complacent, how hatred and comfort can go hand in hand - and how things are always easier said than done. This is for people who state that "they would not have allowed this/felt that/done this/thought that if they were in these situations." 
Survival, emotions, relationships - life is not so simple. 

I was in awe everytime I picked up this novel. 
I see why people say she is one of the best writers to have existed.