Product review (5 stars): Does a great job.
My dryer vent goes up through a wall and out through the roof. First, I blew out my the vent with a leaf blower, then used this cleaning kit.  I was amazed at the amount of lint, that this kit removed that was still stuck to the walls of the vent pipe.  I used a variable speed drill to turn the brush slowly as it ascended through the pipe, and pulled it all the way out in between adding sections so that I wouldn't end up with a big plug of lint at the top.  The rods by themselves without the brush are flexible enough to be used as a fish tape if you ever need one.  Some reviews complain that the sections come apart while in the vent pipe but that can only happen if you reverse direction, which is not necessary.