Product review (4 stars): satisfied, after a little bit of a struggle.
Take this review for what it is, the experience of a guy who has never installed a dryer before now.  That out of the way, this product is sturdy and provides the right angle needed for many installations. I had to kinda fight it to get a good seal and wound up using a lot of aluminum dryer duct tape to make it anywhere close to airtight, but it did work in the end.