Actually, I will be one of the dissenting voices here. I have one and it works well for me. It is quiet enough (the one with the 18 blade impeller) and pulls allot of gunk out of the water. Mine is set up and produces a nice dry foam.
Does it take a little more attention and tuning than others, probably, but aren't you paying attention to something on your aquarium at least once or twice a day (food, lights, top-offs). Not too much to add the water adjustment to this list.
Works fine, no complaints.