This is the first air purifier I've ever had but it seems to work great.  I got 2, one for the bedroom and 1 for the living room.  I bought them because our neighbor smokes inside their apartment and the smell bothers me, I have bad allergies.  Since I've used these, no more smell!  I've also noticed a decrease in dust and the air feels 'crisper'.  I like that the light sensor makes it dim automatically at night.  It's not loud, you can only hear it when it's on high.  Very happy with these air purifiers!