I really love how Revill has used the text to create the iconic form of the whale. This technique is not only very effective and clever, but it is also an excellent way of saving space by combing both text and image together.
This is a great example showing that sometimes the cover doesn't have to be perfect in order to be legible. The way that the text has been written and organised has been chosen to reflect the tone and themes of the book.
Strains combination of strong silhouettes with text background is particularly effective. Normally the silhouettes are a key icon of the story, which makes each cover instantly captivating and also gives you an indication to the themes of the novel.