The overall rating reflects the current state of the app. It accounts for all app reviews but prioritizes the most recent ones.
It imports the dead 404's from Search console for me but the automatic recomendations are not that great. Overall it doesn't add that much over what you can do manually or with a spreadsheet in Shopify. https://www.katysboutique.co.uk
Nice idea and nice app but not worth $9/month in my opinion for what it does.