I'm gonna...
I got quite a bit of Jap from similar apps back when I was in college. Usually done, as you said, on the train ride to school. jap is great for hobby purposes but Chinese is the way I think the futur is headed.
I wasn't sure if I should mention Duolingo in my previous post. I do use it on and off, but whether or not you should depends on your learning style and if you can avoid the game aspects of it from taking over your learning. It gives a lot of completely useless sentences and phrases, and ones the more advanced user looks at and thinks "that's grammatically correct, but still an awkward way to put it", but can help just enough with vocabulary that it's worth a few minutes of your time. If you use it, it should only be a tiny fraction of the time you study and used in conjunction with other things, because it's nearly useless totally on its own. It is primarily a game and ad server, but used right, it can be a just good enough vocabulary builder/retainer. It does get harder to justify using it even for that with every update though.
