I had one for a year before I deemed it ineffective. For starters, it made my room smell like ozone. Two, it doesn't push any air so it hardly filters anything. Three, it was really annoying to clean because you actually have to wipe all the dust (defeating the purpose) off, kinda of like those bagless vacs. Plus, u'd have to close your door to prevent more contaminantts from getting in. If the damn thing just filters what passes by (although it does push a very very small amount of air, VERY SMALL!), how is it going to keep up with the constant flux of air.
I sold it on ebay and got a filter that had a motor, and lifetime hepa filter from target for 130 bucks with 20 dollar gift card. This thing pushes some serious air and my room smells clean, not like ozone. I hardly ever have to clean it, I just have to replace the prefilter (usually twice a year, cheap). To clean the filter I just vacuum it and that is done like once a year so far......Plus, the thing is pretty silent on it's lowest setting but yet pushes out a good amount of air. WHen I get home I'll give you the model number. I got a honeywell model.
I suggest you get a real purifier, not some gimmick. Even still, if you leave a window open, you don't need a purifier because it'll just keep just introducing "unfiltered" air into your room.