Product review (5 stars): Works as advertised!
I purchased this last week and used it this morning, and it works fantastic!  Our 24 ft dryer vent is now as good as new and flowing much better.  (I also purchased the 12ft extension as our vent pipe is rather long.) The whole process, including cleaning out the actual dryer, only took about 30 minutes.

To mitigate some of the issues some reviewers had, be sure to follow the directions correctly.  Most importantly, ensure that you use the tap screw to secure the brush appropriately, duct tape each rod as you connect them, set your drill clutch to half and on the low speed, and take your time.