Instruct: Classify a given review into positive or negative sentiment.
Query: Malfunctioning after only 1 year of use

I've owned this grill for about a year and I loved it at first. But, unfortunately, love fades, and so did the functionality of this grill. The thermostat appears to be failing because the grill no longer holds temperature after preheating. It now takes twice as long to cook steaks and fish as it did when the unit was new. And the non-stick coating has worn off the grill plates, even though I was very careful when cleaning them. Food now sticks to the cooking surface like glue, even when using large amounts of cooking oil. All in all, this product has turned out to be a big disappointment and a waste of money.