This oil diffuser works very well. The glass insert bottle has a great capacity and doesn't need filling very often. It displaces a lot of pure oil into the atmosphere that disperses throughout the room. It produces a very fine mist. So fine that I have not found it to leave any oily residue whatsoever in it vicinity. It is very mobile with the lithium battery that lasts a few cycles before needing recharging. The only draw back would be the whistle produced when in operation, but even this is minor (and I sleep with it in operation on my bedside table), and far outweighed by it's positive aspects. I gave one of these units to my mum who has had bad lungs for most of her life and she commented on the difference it made sleeping with it going at night, which is the purpose I use it for too (with a couple of drops of clove and peppermint in with eucalyptus or lemon myrtle). This is the sort of machine you can walk in, put where you want, have it probably still with battery and oil from two uses ago, and turn on and leave till next time you want to use it somewhere, it even turns it's self off after 2 hours, it is so little fuss. And it doesn't need cleaning out (but of course you can, as the only place the oil goes through is the small glass removable bottle), you just top it up and plug it in if it needs charging.