Have only been using it for about 3 weeks and 'so far so good'!  I do notice less dust/dander (we have 2 dogs) on surfaces but is a little noisier than I expected.  I keep on level 2 just because level 3 would be too much 'white noise' in the room.  I can't wait to see how long the filter lasts (considering we have 2 dogs) because I think they are on the pricier side.