Bought one of these for each of our rooms, after having tried out one in our bedroom for a couple months. The air quality is much improved - fresher smelling and reduced allergy symptoms (I got the upgraded charcoal filter). They definitely pull in a lot of impurities, as I find it necessary to clean the prefilters weekly, because of a visible layer of accumulated dust. I tend not to like appliance noise, but find these to be reasonably quiet on the middle speed (similar to the sound of central a/c running through vents), and barely noticeable on the lowest setting. Highly recommend if you are looking for a high quality air filter!
So far, so good! I don’t use it continuously, and purchased it because of airborne particles. It’s quiet, and doesn’t weigh much so I alternate between having it in the great room or master bedroom.