After about 3 weeks I just took the covers off to clean the pre-filter, and wow the amount of stuff that it sucked up is pretty amazing. To think we've been breathing that in all this time. I will probably get another one for our main room soon, as we have just been moving the 2 we have around as necessary. 

Great price, not too bulky, easy to move around.
The UV light on the front is a bit bright for night time, typically have to turn it off or turn it around.