Instruct: Classify Amazon reviews into positive or negative sentiment
Query: average while it lasted

Product worked well for 4 months, then suddenly failed to power on. Product shows no sign of life whatsoever- extended service is through a 3rd party vendor, so I am guessing that repairs or service will be hard to acquire.Summarized:-product produced cleaner air than no filter at all, yet air quality seemed inferior to other true HEPA filters-clean air produced by filter had a consistent faint metallic smell-product was quiet, providing great white noise at night-oscillations were fluent and gentle-brief product lifespan severely limits quality- I simply cannot recommend this product