Product review (4 stars): Very good dryer vent--clearly beats the flap kind.
These dryer vents are way better than the flap ones.

The only thing holding this back from a higher rating is the way the lid opens.  The other one I got has a hinged lid that you can just pop open.  This one requires loosening the screws--not a good/easy thing when you've caulked everything to keep water from ruining your siding.