Product review (5 stars): Worked Great!
I originally used a leaf blower to blow out our dryer duct when we first moved into our 30 year old home.  A LOT of lint came out and my wife was happy with the results.  Even so, we still decided to purchase this kit and clean it properly.  WOW, it was amazing to see that much more junk come out!

The process was pretty easy.  It took me longer to clean out the laundry fan itself than to clean both ducts.

I used the dryer to blow out the lint.  My duct was pretty plugged up so I cleaned it a little bit at a time.  There wasn't enough airflow to blow out the big chunks of lint, so I had to jiggle the brush around a lot to knock it out in smaller bits.  You definitely do NOT want to get that brush stuck halfway in the duct!  The duct had three elbows.  One was a pain.  It must have been quite plugged.  The brush slipped right through the other two so quickly that I was surprised when I hit the end!