I've been doing
iknow since mid-November. For learning vocabulary and writing kanji, this is the program that worked best for me so far. Of course, it's not intended to teach you grammer, but maybe, one day...
First I tried to study 4 hours a week, but that turned out to be too time consuming, so I went for 3 hours a week = 26 min per day, which seems to be okay, even if I can't do it one day, due to meetings etc.
These are my current stats. 50 hours of Japanese so far :-)