The overall rating reflects the current state of the app. It accounts for all app reviews but prioritizes the most recent ones.
They definitely do not give support, I've called and called and they never answer the phone. The app does not work if you have variants for any one products. You would have to make each color, size, ect. of any product a separate product. It also limits the customer to 1 registry at a time. I would really look at other apps if I were you.