I have chronic issues with my sinuses and lungs due to a toxic exposure on a Marine Corps facility. I also have a 20 month old daughter who, like all toddlers, is very sensitive to environmental variables such as humidity and dust. While we have a fantastic HVAC system and a whole house multi-stage filter, we also have a couple German Shepherd Dogs, carpeting in her room, and wood floors throughout the rest which absorb quite a bit of the humidity when the weather turns cold. So I've been looking, for some time, for a quality humidifier and air purifier, and was having very little luck (mostly going with cheap steam units to avoid mold issues) until we discovered the Oreck WK15500B.Maintenance wasn't a concern for us, there really is no true "fire and forget" solution for both needs on the household market so going in we understood that this was going to require filters, cleaning, and perhaps even descaling (doesn't seem to be a concern). Two features immediately impressed us; one is that the life expectancy of the filter is about 6 months (though no doubt the environment will sway that one way or another), and the other is that the unit has a clever little display that tells you how much life is left in the filter, and how much water you have in the tank. No question that cleaning this unit is going to be a bit of a chore, but we consider that part and parcel of what its function. I would have liked to have seen some sort of anti-microbial treatment/film on the tank, or perhaps a UV bulb -- but in the former case it wouldn't have been permanent and in the latter it would have added an extraordinary expense when the bulbs had to be switched. I can't ding this for either omission. The charcoal filter (odors as opposed to particulates) is a nice extra perk I didn't expect in this sort of product. While we can thank a trusty Diaper Genie for not really having any nursery smells, we do (as noted above) have two large dogs who put off almost as much gas as my wife when they sleep; so that's a welcome bonus. Don't mind that last sentence, I want to see if she reads my reviews.Noise was a concern for us. We've had cyclonic units, clever air pushers with no moving parts, electrostatic cleaners, water atomizers, steam units, wick units -- we've gone through a lot of different options over the years. I'm happy to report that not only is this unit quiet (that's subjective, but I can say without blinking that it's quieter than most and more quiet than I reasonably expected), but it also has a sleep timer that brings it down even further. Again, the WK15500B exceeded our expectations and even hopes in terms of ambient noise. My laptop is louder as I sit here typing.It has a reasonably small footprint, and it aesthetically unassuming. Not attractive, not unattractive; it just looks clean lined and functional, and that's really all I can ask there.Investigate replacement filter cost as part of your research, factor in changing filters every 4 months (perhaps) if you're fighting a lot of different indoor air quality issues, every 6 is what they suggest, perhaps every 8 if your house is uncluttered and kid/pet-free. Your mileage will vary.As far as the unit itself, we really couldn't be any happier with it. Wouldn't begin to know what else I'd want in such a unit. Highly recommended, and I see us getting a second one.