Excellent! 
Very smooth working, cleans the air and solved my allergy problem.
Big, but good.
I realized that I had a terrible dust problem in my office, so I bought this thing.So far I have had it for a couple of days, and it has a noticeable amount of dust on the odor grabber part, so it surely is doing something.
When I opened the box, I was amazed of the sheer size of the thing! Its much bigger than I would ever have expected!
When turned on its lowest setting its very quiet but I noticed when turned on its 2nd and highest setting I was overwhelmed with the noise. Well after having it on for awhile I am used to the noise it makes, I guess its not really that bad.
Well worth your $30 or so American dollars...
Pros: Not too terribly loud, it works...
Cons: The filters cost more than a drunk hooker on a Monday at 12:00AM.....$15+ (a piece)! oh my, well deal with it.
Great filter, but... 
This small filter did a great job taking care of a litterbox dust and odor problem. It's fairly inexpensive, but keep in mind that the filter is only something like 6" x 4" so it has to be replaced fairly often.
Two replacement filters are required: the HEPA filter ref. HAPF22PDQ-U, and the carbon pre-filter, ref. HAPF220. Unfortunately Amazon no longer carries the HAPF220, so keep that in mind when making your purchase decision. Had I known I would have picked a model for which Amazon carries replacement filters!
Loudest thing ever
Its advertised as whisper quiet. Well, its not. The instructions say for continuous use choose the high setting. When it is on high it is extremely loud, like a good size table fan on high, at least. There is no way I could sleep with this thing in my room. The low setting is not as bad but still quite loud. For the price it cleans the air well, but describing it as whisper quiet is fraud.
