Well I just purchased this air purifier after extensive research on-line--this machine seemed like it was the best value and quality for its price range. There are other machines ranked a bit higher but they will cost at least $100-$200 more and it didn't seem like you would begetting that much more value. I decided if we liked this one in our bedroom it would still be cheaper to buy a second one for our living room than to buy one of the other brand's larger and more expensive versions.It came today and within an hour my boyfriend and I both seemed to already notice a difference. The air feels fresher and cleaner--and smells better. Not to mention it is really quiet--even on high. The only mode that is a bit more noticeable is Turbo and even that just sounds like a fan turned on high. It was easy to set-up and is easy to use. I will have to check back in again after a longer period of use to report on whether we experience a long term noticeable difference on our allergies.