The arbitrariness of star ratings is a tricky aspect of appraising books, films, music, plays – or Airbnb kitchens. In Benji Wilson's breezy, enjoyable Rate This Book: How Star Ratings Took Over the World (New Modern Arcade), the TV critic unpicks the history, psychology, trustworthiness and impact of those little classification symbols, which are taking over every area of modern consumer life. It perhaps won't be too long before a person's death earns its own ranking.