Product review (4 stars): Works how it's supposed to in the winter.
This was really easy to install and took me all of 10 or so minutes.  Most of that was spent wrestling with my drier hose.  Since the air is already being vented into the laundry room there's no issue.  When summer comes around I may have to take the product off.  The unit itself has gaps in the plastic.  I may have my husband seal it with some caulking or we may just remove it in the warmer weather.

Since we live in such an arid climate this product is perfect!  It keeps the back of the house warm while the drier is going and adds much needed humidity to the air.  In climates that aren't a desert I'd be cautious, as it does put out a good amount of humidity.
I don't feel as bad using the drier rather than my drying rack while using this product.