We've had this air purifier for a few years now. Frankly, I'm amazed the thing still works! We have lots of pets, and two kids, so if it can stand up to that for years on end, I'm pretty impressed.
This purifier contains ozone technology. So, if you leave it on too high for too long, you'll get an almost choking bleach smell in the air, and it can start to hurt your throat and eyes. Don't make that mistake. Keep it about in the middle, with a boost up to high every now and then when you need some really quick purifying.
It's easy to clean. Just take the glass ozone plate out of the back, run it under the faucet for a little bit on both sides, towel dry it. Take the filter off the back, and you can pretty much do the same thing. So, you don't have to replace the filters! Which saves money in the long run.
Also, as you can probably see in the picture, because we have so many animals, and people, creating so much dust and so many icky things in the air, I need to vacuum it out now and then with the hose attachment on my vacuum cleaner (which, obviously, I have neglected and need to do soon, lol).
It really has been a great unit! And, it came with an additional ozone plate, that you can use, full instructions, tips, the whole nine yards. And, I've been really impressed with the company. They're easy to get ahold of, and they treat you like a real person, rather than a number.
It's not noisy either. I hardly ever hear the thing at all. But, if you have it up really high, you'll hear the fan (about on par with your average household fan).