I saw a Dutch guy using it this morning, he has used them many times and had no problems. Seemed very quick , just a few minutes. It looked as if the outside had been washed, don't know about inside the tank, didn't get that close. It may be a bit of a gimmic, since I started using the bio washing tabs, i think the inside of the tank has been well cleaned, I can easily wash the outside. I know its only a euro, but I don't think I'll risk sticking the cassette in it.