I've always wondered if faucets were worth any time at all. Apparently they really aren't. But I think for anyone looking to have some fun doing a couple of rolls here and there it's not a bad way to pass the time. But by doing that I guess you wouldn't be doing anything productive at all. I wish Duolingo had Japanese, I need to learn some before heading there in the summer.
Memrise is similar and has Japanese. Used it for a while, but I got bored with it just like I did with Japanese Rosetta Stone and German Duolingo. Flash cards and textbooks are better IMO.