Quiet. Simple. Works like a dream.
I got one of these to put in the bathroom where the cat box is.  It's also the bathroom where my 4 year old boys frequently go, and though I do my best to keep it all clean, smells happen.  I plugged this thing in last night, and the cat box smell was gone this morning. I will be ordering more. We just moved to a new house from an old moldy house that liked to make us sick, so I am on a mission to find the best air quality products for my family.  Granted it's day 1. If it fails prematurely I will update my review.
Rating: 5 stars