Product review (4 stars): Great if you need the extra space it provides!
Got this mainly to replace a hose. Thought I would try an alternative since this device lets me push my dryer back closer to the wall. Installation was not exactly easy and required a good amount of aluminum duct tape, but here's what I had to do:
Completely remove my washer and dryer out of the room (my laundry room is small and tightly packed). Then I had to size the vent from my dryer to the outside vent hole. I had to cut the excess aluminum off with some snips. I also used a pair of scissors, as it made some cutting angles easier. The parts I cut were extremely sharp.
I then almost completely wrapped the vent in aluminum duct tape to cover all the holes and gaps so no air could leak through. Since it's adjustable and slides, it has a lot of cracks and gaps that was needed to be filled. I even taped the cracks in the vent holes, which did prevent them from rotating, but I wasn't bothered by that. I just wanted no hot dryer air to leak out at all.
I then connect the vent to the outside vent hole, then with some help, slid the dryer into place while lining the vent holes up. All done!

One problem with this vent, as opposed to a hose, is that you can't move the dryer around once you set it in place. If you do, you may disconnect the vent, which, in my case, means moving our washing machine out to be able to reach the vent connections again.
Another problem is that I had to use a lot of aluminum tape to properly seal it, which was tedious. But no air is leaking out and our laundry room doesn't get hot at all anymore!

I definitely recommend this if you want to be able to push your dryer back as close to the wall as you can (2 to 3 inches for me). But if you aren't concerned with needed extra space, I'd stick with a regular duct hose. It's much more hassle free and easy.