Instruct: Classify Amazon reviews into positive or negative sentiment
Query: disappointing

These balls didn't last as long as regular Wilson tennis balls. It took 2 days for my dog to destroy the first ball. I gave the second one, hoping it was just a fluke, but she knew just how to break it open and this time it only lasted about an hour. The old tennis balls that a neighbor gave us are still fine and much bouncier. Save your money.