It worked for me when I studied Japanese, German and Russian, even though the language of instruction is English, which is not my native language. The trick is that you have to follow the instructions, not just "listen to some tapes". The Japanese course consists of 3*30 units, the recommendation is one 30 minute unit every day. Do that, no more, no less. It's not magic, even if you master all 90 units, that's just a very basic spoken proficiency. But it gives you that result reliably.