We've had this air purifier now for more than a month, and I am so happy with this purchase. Within a day or two of setting it up in our bedroom, I stopped waking up with a sore throat. We leave it on auto mode, and it is so quiet. The only time you hear the fan is when the air quality in the room needs help--and even then the noise isn't bad. 

It's also very light, making it easy to move to around as needed.