Yes, it is. The unit is very sensitive to dust and smells (e.g. cigarette and kitchen smoke). It is definitely noticeable.
It is also noticed by our visitors.

I have only been using the Mi Air 3H for a few days and cannot say much about the filter behaviour yet. However, I assume that the dust will be reduced. The fan makes a high-quality impression. But what is very annoying is that the sensor only reacts to PM2.5 particles. Large dust particles that "dance in the sun", for example, are not detected by the sensor. So you can't automate the control as far as visible dust particles are concerned. For the smallest particles (-> e.g. pollen), of course, it can.