I've read two "official" reviews that complain about the noise,and saw an independent rating down to only #3 in air purifers, (with two less powerful Honeywells at 1 and 2.
Anyone who does not want the noise can turn the device down a notch,and then get the best air purification for the silence.
I can turn it down very low so that the sound does not disturb conversation, listening to music, or a movie, even when I'm following it in a foreign language, and only three feet away.
The noise at night, when I put it on high, works as good white noise against the clamor and traffic outside, but the middle speed would be satisfactory to many who don't need the white noise.
But if you want to use it in a room you are not occupying at the time, or really need the extra air purification that I need, especially as I asthmatic, have chronic overnight-sinusitis, and laryngeal spasms, especially with the smoke of neighbors that fills the walls up and down (vertically) the entire 15 floors of the building on both sides of my apartment, then you want this air purifier.
If you want to choose something that will never do as quick a clean-up of the air you breathe,, then buy a less expensive Honeywell. I have used three other brands of air purifiers, but Honeywell is the best for getting the job done, and for its durability (I sold one when I was moving, and one was stolen, but I used each for several years with nary a problem.. If Overstock comes out with yet a stronger model of the Honeywell, despite even louder noise, I will buy at least one of them.
Overstock has been my savior in saving me money and delivering for free with Club-O, as I am disabled and do not own a car. I only wish I had joined it earlier.,