To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyzes reviews to verify trustworthiness.
This will be difficult for any beginning English speaker to use. The introductory information is spoken rapidly and will not be understood by someone learning the language. The "exercises" only pronunce the words once with little time for the student to repeat the word. I can see lots of students getting frustrated with this program very quickly.