The smell of this is lovely, not overpowering or chemical smelling like so many diffusers are. I have noticed it has had some calming effect on my cats but it is being used in a large area so clearly the effect will be limited and is certainly better than other calming diffusers I have tried previously. I will continue using this product by purchasing refills because I would miss that gentle background aroma if it wasn’t there. I have absolutely no negative comment to make about this diffuser.