Instruct: Classify an Amazon review as either positive or negative.
Query: Poorly implemented illustrations

While this book does deliver exactly what it promises in the way of content, there is a significant flaw in the illustrations, which are essential for a book of this type. The introduction explains that the object ball will be black and other balls will be grey. Unfortunately the reproduction of the grey balls is basically black.Under bright lighting and close examination you can see a slight difference, but it's much harder than it should be. Perhaps only this particular edition or run has this problem, but it significantly detracts from the readability. On the more complex shots it takes careful deduction to associate what you are reading to the illustration.