Product has been excellent and I use it most days due to overheated room. Lower two fan settings are very quiet and in the hot summer I have it pointed at my bed to knock 5-8 degrees off the temperature. Handle makes it easy to carry and very portable, especially given the USB power supply.
Replacement cartridge is good. Same quality as the one that comes with the unit. It is easy to replace as well. I don't know if replacing the cartridge really has any benefits though. I'd like have more information about why it needs replaced and how you can tell that your cartridge needs to be replaced.