Was recently in Honduras with my travel buddy and he had these with him.  I thought they were a rip off at first, but then over the course of the trip became envious of his packing cubes.  Upon return I bouth some of my own to test out for my trip to Iceland/ Europe.  I was pleasantly surprised with their utility.  They are a very simple concept, but if you are the move with your luggage it makes getting in and out of them for one specific item a whole lot easier.  I very much enjoy these and plan on using them for all upcoming travels from backpacking, formal traveling, camping, etc.