Only have been using it about 6 days now.  Seems to working just as described.  Very, very quiet no complaints so far.  I am using it in a home with 3 large dogs and mostly using the unit on "Auto" in a fairly large living space and I can tell a difference in the air quality.  I have noticed when the dogs come in from outside and run around the unit, the unit does properly adjust and the bar light turns amber for a bit.  I have used it in the bedroom 1 night and no complaints regarding noise at all.  So far happy  and pleased with this choice!