I think it is missing a way to visualize our progress about new words, a way to visualize the efficiency of the method.
For instance, how can I see the progress over time of learning words?
A graphic showing a line going Up (remembered) and Down (forget) for each word over time would be something.
How to visualize the latest new words that I did not know? Many words I already know, and I am just remembering from other courses, despite the system consider it as new.
I think the feeling of "localization" in process of learning can better localize the student in the learning process. Visualization is the key and very motivational. We all like to see some good graphics showing our progress.