I have one and it felt nice, unfortunately because people smoke in the building I live I can't use it since the smell collects in the filter very quickly and they are expensive (but last a long time if not for the smell). A bunch of carbon could help with that but a) I try to avoid stuff from low wage countries as the carbon is (but not the rest of that particular air purifier as far as I could tell) and b) hopefully I can just move in the not extremely distant future.
There are a few others as well, look for the better quality filters ("SuperHEPA" as AirPura calls them). As I understand it, the small particles are the ones that aggrivate allergies the most and that is exactly what the higher quality filters are better at. Only a relatively few companies have those better filters, IQAir is another one. It turns out the name HEPA doesn't mean anything for consumer filters, you need to look at the specs.
So just make sure to not place the air purifier in a corner, but more central. And turn it up to a higher power. Or run your AC fan continuously