Started using the pair as soon as we got it. One upstairs and the other downstairs. Works just as described in the manual and really easy to set up and operate. We have a 3400 sq ft living space with centralized air handling system equipped with HEPA filter as well. Since we have only used it for 5 days now it may be too soon to judge it's effectiveness. The indicator for the air quality is very informative and accurate as manifested with air movement due to HVAC in operation or just house occupant activity. Very quiet and actually soothing. We'll provide more feedbback as we go along. Actually bought the pair due to my wife's extreme allergy to dust and pollen. So far it is great.