I don't have an ultrasonic humidifier, but I do have an ultrasonic diffuser. Though basically it does the same humidifying as the smaller humidifiers, just with a smaller capacity for water. Mostly I use it for nice essential oils, but also for leaning over it and inhaling anti-bacterial oils after a Neti pot when my sinus infection flares up.By comparison, the ultrasonic humidifier approach to halogeneration is a much cheaper and much more straightforward means of saline air generation that can be used at leisure in your own home.
Awesome things, wish I'd known about them years ago!