"It works!"
It really works. It is amazing, but true. I follow the instructions and I remember the words and expressions. I'm through phase 1, and although it's pricey (1 credit for 5 lessons) I plan to continue because i see the results. Even my 10 y.o. wants to learn. I listen in the car, but later at home I do some additional exercises or listen to the German broadcasts. I have learned (apart from English) Russian and French at school, but this method is by far more effective.
"Just right for my 9 y.o."
If your kids enjoyed other books from "The 39 Clues" series, they want be disappointed. To me this series is like a pack of vitamin candies - kids love them, you know there is not much nutritional value in them, but you yield once in a while (in this case "vitamins" are some geography and history).