Let me preface by saying I have tried countless apps and self study programs, but none of them helped me grasp the concepts of Japanese.
I have been learning with Yoko-sensei for just over a year now and must say that my comprehension and speaking skills are a night and day difference.
I have been using apps for years and was never able to grasp things the way I did with Yoko-sensei.
Highly recommend Yoko-sensei has been nothing but a pleasure to learn with!