Product review (4 stars): No matter what tool you use-clean the dryer vent.
I did not particularly like this product, which I bought along with the extension kit. The tubes must be screwed together, and somehow while inside the vent it came apart. I'm not sure if it was my fault or just poor design.  In theory it ought to work quite well.

I should have stuck with my "old" self designed system which is:

1. A long extendable tool designed for high dusting with a round brush (bought from Costco) attached that fits perfectly inside the vent. It's just big enough to brush the grooves in the vents and get the lint that can stick to the sides.
2. A heavy duty wet/dry vacuum with a very long hose.
3. A leaf blower!
I use the vacuum outside and the blower inside, back and forth until I'm satisfied it's as clean as possible. I use the dusting tool to get the grooves, if needed.

For those reading this, the tool is worth it for most people who regularly clean the dryer vent.  Just take care in how you put it together.

I recently helped a friend clean her dryer vent, which hadn't been done in years. Someone had actually covered the vent with a screen (great idea) but hadn't cleaned the vent beforehand. The blower/vacuum method was critical in this case.
The vent was packed with: 2 or 3 robins nests (straw, weeds, dirt, brush, broken robins eggs, and lint that hardened on pieces of straw at the very back.  The next day a load of towels dried in 30 minutes less than "normal." I want to see the next electric bill. More importantly, her house didn't catch fire.