We bought two of these, one in our bedroom and one in our sons bedroom and I can't say enough great things about these air purifiers.
Yes..they are very expensive and Yes the upkeep (filters, etc...) are expensive, but, I do feel that these have made a HUGE improvement in our asthma and allergies. We are sleeping so much better now. I have never had a purifier that cleaned the air THIS well.
The quality of how well these purifiers are made is superb. Each unit is tested and certified. How you ask? Well....each unit is tested for particle filtration efficiency, filter leakage and air delivery. Each unit is issued with its very own two-page Certificate of Performance, detailing the test results for that very machine.
What is also very impressive about this purifier is the Intelligent Filter Life Monitor display that actually tells you how many hours you have left on the filters and it's NOT just a timer. The unit actually comes up with the number based on air quality and fan speed.
I also love the fact they are energy efficient, which is achieved with a very efficient fan and an advanced fan control setup. As a result, it costs only pennies per day to run.
I would highly recommend the IQAir HealthPro Series Air Purifiers!!