Instruct: Classify the given Amazon review into positive or negative sentiment.
Query: Unreliable, chunks left no matter how long it runs

We bought this coffee grinder at K-mart because it was chrome colored. But, it has been terrible. Sometimes it decides to only grind for a few seconds before it stops. Then you have to stand there and repeatedly push the button to keep it going. Even when it runs for a longer time, it never does a good job grinding the coffee. There are always big pieces left. It is useless. Don't waste your money on this dog.