Product review (3 stars): ok.
I originally reviewed this at 5 star, but have since changed my mind.  The first filter we used was great.  When I re-ordered these filters they left a film around our (glass) glasses.  It is not noticeable on the plastic cups, but on the glass cups it's very noticeable.  For being a generic brand, it works for the cost, but was slightly disappointed after having such a great result the first time.