Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Don't buy this!

I fly a lot... I'm an airline pilot. My daughter gave me this heater as a most welcomed birthday gift. I followed the attached directions yet it inexplicably failed to work after using it only 4 or 5 times. i was stymied trying to determine how an object so simple could suddenly stop functioning! Coming here to read online consumer comments in a quest to find a replacement led me to learn of its design to fail. Save your cash. I wish I could find a portable alternative.