Three Skulls Good
Solid, entertaining, well written, and good value for money. Three skulls is the average, and highlights books that you will probably enjoy.
Four Skulls Genius
Engaging, intriguing, unique and well put together. If I give a book four skulls it's because it shows excellence in style, theme and construction.
Five Skulls Epic
Mesmerizing characters, thrilling story line, awesome cover, distinctive style, fresh voice and an unbreakable plot. If I give five skulls its because the book blew me away. It would be something I have not read before. It will leave a deep impression, and will be a story I read repeatedly for simple enjoyment.