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

Buyer beware -- Received this heater free from the manufacturer to replace an oil-filled heater that leaked oil within the first year of use. The Bionaire was silent and worked well until the on/off switch quit working after several months of use. So it went out in the trash and I won't be buying another micathermic or oil-filled heater -- free replacement or otherwise!