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!
Spaced repetition is the best scientifically confirmed way to remember stuff you need to remember. And here you choose what to remember!
No cons. May be the interface could be a bit more flahy but I personally do not care.