The audio lessons are presented very well. They are by far the best part of the program. The written tests and multiple choice tests work fine. The interactive voice tests are sometimes glitchy. As others have said, the website and iOS app can sometimes have issues. The iOS app is not as quite as fully functional as the website, but still pretty good. Overall, I'm happy with the program. I suspect it will continue to get better with time. I'm not disappointed with my purchase.