Product review (4 stars): Works well
The only downside to these vents is the plastic they are made of.  I painted mine to prevent UV damage and brittling.  I have one installed on the masonry wall of my house and it works very well with my gas dryer.  A small aluminium extension tube is required to pass through the wall and into the vent but no other parts are really required.  I installed a twist lock breakaway fitting on the interior wall and it has been working well for about five years now.  I clean it out in the spring and I'm good all year.  My parents had one on their house for over 15 years and replaced it when the siding was changed, the vent was still in working condition.