Product review (4 stars): The kit did an excellent job of cleaning all of the lint out
I ordered this duct cleaning kit because I have a ten year old dryer - that has never had it's duct cleaned.  I was absolutely certain that I was ripe for a dryer fire, so I ordered this kit.  The kit is very well made and simple to use.  Imagine my surprise when I  cleaned my old ten year old duct and got only about 2 cupfuls of lint out of the 10' long pipe!  The kit did an excellent job of cleaning all of the lint out, but that was all that had accumulated in ten years - 2 cups!!
I believe the small amount of accumulated lint was due to my wife's absolute dilligence in cleaning out the built-in lint trap before every drying session.  I believe that those who report significant buildup are those who do not clean the lint trap regularly.  Before spending 20 bucks on this cleaning kit, I'd advise to visibly inspect your dryer hose to see how much lint is built up.  I could have easily gone another 10 years without burning my house down or having lint build up affecting the performance of my dryer!