3rd air purifier purchase for me. I have 2 Alen 350's, one I use for allergies and another my mom uses for a pulmonary condition. This new breathe smart purifier compares well to them. It is larger in size than the 350 but it covers a much greater room area. The purifier is very quiet on the first 2 settings, perfect for sleeping, settings 3 and turbo are louder but still not nearly as loud as the highest setting on the 350. I utilize the auto smart sensor as this purifier is in my family room. The only time I really notice the purifier running is when it is on turbo. The purifier is simple to set up and use for the first time. I would highly recommend this purifier.