I have three of these units and I couldn’t love them more. I run them nearly constantly in the winter because the heated air is so dry. I like a strong fragrance so I use 30 drops of essential oils, but even just a few drops makes the room feel “fresher” and not 
overly scented. I leave them on one color all the time and it adds a nice glow to the rooms. Guests always ask how I keep my house (with kids and a dog) smelling so fresh and they love the look. Several have purchased one for themselves after visiting.