Product review (5 stars): A Great Mr. Fix-it tool
Follow directions and you should get as good a result as I did.  Our dryer vent took the full 12 feet of the rod sections they provided.  I pushed the brush up to the vent cover and then hooked it to my drill (turning clockwise only) and brought it back out.  I got a lot of dirty lint that I had failed to remove using a shop-vac.  A bit of a messy process, you will want to have your vacuum handy to pick up all the junk.  Duct/Duck tape the joints so they don't separate inside your duct.  Inexpensive purchase for your Mr. Fix-it tool kit.