From what I can glean from the reviews on Amazon, this book (and the series) borrows heavily from The Lord of the Rings. Having not read Croggon's book, here's what I believe, based solely on the cover: Where Tolkien's world is both bright and vibrant and dark and ominous, Croggon's world is drab and dull and ugly. A weak sun and a bleak landscape surround characters who hold little interest for the viewers. The boy either has a haughty expression, looking down his nose at the reader, or is about to sneeze. The girl is holding a lap harp, but does the picture engender any interest about her playing abilities? No. Do you wonder where they are going? Or why they stopped here? No. Surround that drabness with orange and you have the epitome of boring.
At least with American Gothic, you wonder what the lady is looking at, why her husband is holding the pitchfork tine-side up, and where they got their ugly curtains.