I was very pleasantly surprised with this air purifier. I was a little worried because the cost seemed low for what it is, but this is a very nice unit. It is about as loud as a stand fan on its highest setting, but on the low setting it's really just background noise. I like that it's very easy to tell the UV light is on. The night mode dims all of the LED lights and really does make a huge difference if you're using this in a bedroom. After just one day I could tell there was a significant improvement in the air quality throughout my entire apartment.