In the 4 or so years I've had a refrigerator that uses these filters, I get about 3-4 weeks of acceptable flow before it becomes a trickle.  By two months my water dispenser is useless.  I have also spent more on these "filters" than on the relatively high-end refrigerator I use them with.  Even now that I am installing a reverse osmosis system instead, Frigidaire wants essentially the price of a filter for a blank that will allow water to flow unfiltered.