The overall rating reflects the current state of the app. It accounts for all app reviews but prioritizes the most recent ones.
The idea is great, the execution, however, is not even close. It is impossible to add products in bulk which makes configuring this a terrible pain, the products that are supposed to be off are still appearing with a different process, and if you wish to check a report on how the plugin benefited you then you need to check manually every single product. Long story short good for a microsite with only a couple products.