I love the Fit50! The air in my house is so much cleaner since I got it and I can't believe how quietly it runs. My favorite feature is auto. I never realized how much dust could be kicked up just by someone walking around. I have to admit it gives me a little thrill whenever my dogs or family members start moving around and I hear the Fit50 shift to a higher speed because it sensed the change in the number of particulates in the air. For someone that suffers from allergy/sinus issues like me, this is a wonderful machine.