We now have 4 BreatheSmart units throughout our home (and two smaller units to cover smaller areas), all purchased at different times over the past 5 or so years -- so this should speak to how satisfied we have been with the overall quality and usefulness of this product. 
Alen Corporation does honor its lifetime warranty and on occasion when an item does need to be returned (we had a couple over the years that had to be replaced when the motors started making uncharacteristic sounds), they have made the return /replacement process very streamlined and non-intrusive on the customer. 
The product could not be any easier to operate and maintain. Filter replacements are extremely quick and easy. Highly recommend.