Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Sudoku Grand Master should be called "If you're an idiot, you'll buy it."

Pieces slide all over the board so that you can't keep track of what you've done. Also, the smaller "maybe" pieces are too small to handle easily and slide around even more than do the bigger, final-choice pieces. Velcro should have come into the picture on this one.