Product review (5 stars): Money Saver!!!!
After receiving a quote of $175 from a dryer vent cleaning service, I found this product on Amazon and decided to give it a try.  It was very easy to use, just be sure to read the instructions first.  I used the dryer to blow air through the vent with the fan guard installed, so I can't comment on the effectiveness of the vacuum attachment method.  Our vent is 7 feet long with two bends and I had no problem pushing the brush past the bends.