Product review (4 stars): Almost perfect
Installation was a little hard.  My house has a brick exterior so I had to drill into the brick.  The mounting holes on the top are partially obscured by the vertical vent exhaust making it hard to get a screwdriver head back there to sink the screws into the holes.  The unit functions as advertised though.  Clothes in the dryer don't get nearly as cold.  The draft from the outside air is pretty much gone.

Pros:
Stops almost all draft from outside
Will help reduce heating bill
Easy access to clean out lint.

Con:
Top mounting screw slots are hard to get at which may make installation a little harder.