I love this air purifier, this is my favorite one that I have had. It is so easy to use. The best thing is the technology - it adapts to the environment, adjusting its level depending on what's happening in the space.  I am using this in the room with the cat box and what a difference it makes.  I have not yet had to deal with the filter but the system works great. I honestly have no complaints, it works great and is really easy to use.