Product review (4 stars): Very good product
This product does exactly what it should do.  It really works well in cleaning the dryer vent.  Mine goes through the wall up to the roof and is not easy to clean.  This is probably the best product that I've seen or used for cleaning these vents.  My only negative about this is that the vacuum attachment does not fit the hose of my shop vac or for my regular vacuum cleaner.  The Vacuum Adapter is meant for a a 2.25" hose or a 1.75" hose with the included reducer.  The hose on my "Shop Vac" brand vacuum has a 1.25" hose.  I ended up putting the vacuum hose into the vent while using the brush and it worked fairly well.  It would have been better if there was a smaller adapter, however.

The sticks for the brush are rigid, but flexible enough to go around curves but strong enough to not flex inside of the vent while cleaning.  You can also use them to fish wiring in the walls also as an undocumented bonus.  This is a very good product and I would have rated it 5 stars if not for the vacuum attachment.  I'll make a reducer that works but I'd highly recommend this product.