What is a Good Book Cover?

I don't love this book cover. However, I do think this cover is a success. The reason for that is because it depicts the novel's mood and story line really well. I have a love- hate relationship with this novel but even without reading the novel, one can already know that this novel is not a comedy or happy type of novel. It's an autobiography and the black and white photo of a young girl with a scarf covering her face really gives off an eerie, kind of depressing feeling. That already shows in itself that the story line is going to be sad. Also it shows irony since the title is Autobiography of a Face but the girl's covering her face.