Product review (5 stars): Holy lint storm!!
I wish I had pictures... Our house is fairly new, about 4 years old. Our dryer duct run is fairly long, about 23' total, with two 90 degree turns. The cloud of lint that came out of the duct was amazing. My advice would be to wear a dust mask, seriously. I cleaned the duct in about 10 minutes, and will make it a yearly maintenance item from now on, for a fraction of the cost of having it done professionally.