The overall rating reflects the current state of the app. It accounts for all app reviews but prioritizes the most recent ones.
The Gift And Gadget Guys
Page says it does 3 things - alt tags, compressions and image resizing/cropping.
Take note - it may have done this in the past but now it only does TWO. Alt tags and compressions work fine.
It no longer does image resizing/cropping.
Wasted my time.