I’ve used Keurig cleaner regularly for almost three years now.  I’m always amazed at how fresh a cup of coffee tastes after a cleaning, as if the brewer was brand new.  Prior to this in other coffee makers I just used vinegar but I’ve never had a coffee maker last this long so I’m convinced this cleaner adds to the longevity.  Aside from the cost of the cleaner I’m still ahead because I’m no longer buying other brands of coffee machines every year.