Product review (4 stars): Gardus RLE202 LintEater 10-Piece Rotary Dryer Vent Cleaning System
Noticed some lint accumulation at the dryer vent outlet so picked this up to deal with it. Brushes are soft but effective and the rods are flexible enough to make 90 degree turns. A surprising amount of lint came out of the vent and dryer itself, so I'd say it was very effective.  Cannot speak to the effectiveness of the vacuum attachment since in my case it was easier to brush the vent with the dryer running, using the dryer fan to expel the dislodged lint.