Product review (5 stars): Lint Be Gone
I have an incredibly long run from my dryer to the vent outside.  It's over 35 feet and has several bends, including one that is 90 degrees.  My dryer no longer dried my clothes without taking an extra 40 minutes, so I figured that the vent was the culprit.

I ordered the extension kit as well since the run was so long and I still had to run it from both sides.  I thought that the tool would have no chance to navigate the 90 degree bend, but I was wrong.  This is an amazing product.  The lint came pouring out in a huge pile.

I can't recommend this product enough.  Easy to use and effective.  The only gotcha is that you need to make sure your drill chuck is big enough.  I had to borrow a buddy's 1/2" drill.  No biggie.