Product review (5 stars): It just works
There aren't many cheap alternatives to to venting a dryer out an interior wall. If you go up through the roof you have to buy a $200 booster to make it safe. There ae ventless dryers but they are expensive and seem to be getting mixed reviews. So this is really the best alternative even if it isn't very aesthetically pleasing. If you don't keep water in it, it's useless and the lint will go flying everywhere just as if you used nothing at all. So you do have to position it somewhere that is flat and easily accessible. I bought and extra vent extension with a 90 degree angle so I could run the vent straight up from the back and then over to the side with where I have the trap sitting on top of the dryer. This takes up less space and makes it easy to access.

You could probably rig up something like this yourself with a bucket of water and some vent hoses but for less than $15 why bother?