I ordered this product because I couldn't afford Rosetta Stone. I had read many mixed reviews, but figured I'd keep an open mind, and if it wasn't effective, at least I'd only be out about $30.
What I found was that this product is great at introducing vocabulary and assessing it (testing you), but not very good at teaching it, at all.
In preparation for my upcoming trip to Germany, I've begun watching my boyfriend's daughter's Muzzy German language videos, and listening to the CDs in the car. I've found this so much more useful in learning contextual language, beginning to piece together meaning and being able to then use the phrases I learn at appropriate times in conversation with my boyfriend (who is fluent) and his daughter (who is semi-fluent.)
I strongly suggest that if you want to really learn the language, you acquire the Muzzy videos and watch them over and over, listen to the cds, and save up for Rosetta Stone. I found this product to be relatively useless. The gains I've made while using Muzzy have been quick and made me feel much more confident about my upcoming trip abroad, and my ability to communicate to some extent!