Spaced repetition is the best scientifically confirmed way to remember stuff you need to remember. And here you choose what to remember!Cons:
No cons. May be the interface could be a bit more flahy but I personally do not care.
I use it for a long time now. And you know what? I speak 8 languages by now. Not counting the programming languages, only the natural ones. And I use ANKI for everything, not only that!Anna Aljanaki has used this product for one year.