About a week ago I started with Duolingo. And I find it really cool. And what is more important - I find it useful.
It has different exercises - translate, select right variant, write what you heard and so on in different areas.
I do the trainings on the way to the work and back when I use public transport. And it work for me.
Moreover, it has features I would want it has.
- I did an exercise in a train and when the task was to say something, there was an option like "I cannot talk now" to skip "saying" tasks.
- It understood minor mistypes I did
- It knows that some German sentence can be translated as both, "I do" and "I'm doing"