Product review (4 stars): It's better than we expected
We have a large chest of drawers sitting over our heat vent in our bedroom, and it was blocking the majority of our heat and leaving the bedroom freezing!  We did quite a bit of shopping around for a product like this, and based on reviews, they all seemed flimsy and worthless.  So I suppose we bought this with lowered expectations, but it's doing the job we needed it to do!  The room is significantly warmer.  A good indicator was that the clothes in our bottom drawer were always warm like they were just out of the dryer, but they aren't nearly as warm anymore, indicating that the heat is definitely being deflected out from underneath the dresser.  It did come with just one clip, so the sides of the vent extender are not secured, and I imagine we are losing some heat from the sides when the air kicks on and blows it up a bit, but overall it has improved our frigid situation!  I agree that it is definitely over-priced, but with shipping and handling, buying a product like this from any site ran about the same amount.