I think that many people trying to learn a language waste way too much time memorizing words and grammar rules. Some things cannot be learned from textbooks. For example your ability to understand spoken word - are you able to understand instantly without translating in your head? You can acquire this skill only through practice.
This app will help you practice with authentic audio content. You will improve your listening comprehension, learn many words from context, and develop your feel for grammar. In my experience, this is a lot more efficient way to learn languages than traditional textbook learning... and it's fun.