Product review (5 stars): Works Wonders...BUT BE CAREFUL!!!
Our dryer over the past year started taking longer and longer to dry our clothes.  I first checked all the visible areas in the vents.  I cleared out all the lint I could get at (and there really didn't seem to be much).  Sadly, that didn't help at all.  Next, I took apart the whole dryer and cleared out any and all lint I could find...there was a bit there, but not enough to impact the efficiency problems we were having.  Finally, I decided to take the plunge and purchase this kit.

Wow...there was a lot of lint and other stuff in our vent line that was not visible.  By other stuff, I think there must have been a mouse living in our vent because the stuff that came out was more like nest material then anything else.  There were clumps and clumps of this stuff.  Afterwards, the dryer was back to its old self and drying clothes like a champ.

So things to keep in mind:
- Read the instructions CAREFULLY.  The instructions clearly tell you to only turn the drill in the forward or clockwise direction.  IF you run it backwards, the rods can disassemble in the vent line.  If you're using the extenstions, then this can be a big issue.  I stupidly and accidently ran my drill backwards and had 2 rods and the brush attachement get stuck in the vent line.  I couldn't reach it by hand so I had to get into the crawlspace under the house, open up the vent (and it was well duct taped), and pull out the rods by hand.  It was not pleasant.  The company does sell a retrieval tool for about $13 should this happen to you, but I didn't want to wait and I also didn't want to spend any extra money so decided to fix my mistake the hard way.
- Other reviewers have mentioned a how to DVD...the newer version of this product DOES NOT COME WITH A DVD.
- You need to use a vacuum on one end of the vent to suck out any lint that gets pushed through by the brush head.  I used a normal vacuum with a smaller hose.  The instructions recommend a shop vac, but the kit does come with a small hose attachement.  Just use some duct tape to create a good seal and check the hose intake line frequently to make sure it doesn't get jammed up.  I had to clear the line about 3 times.

So...if you have a dryer that's lost some efficiency but is still creating hot air and is blowing air directly out of the back of the machine, you most likely have a clogged vent line.  This product, when used right, is very easy to use and is very effective.  Highly recommended!