The App charges for all the orders irrespective you generate shipment label or not... In logical case, the charges should be based on the labels created.
Let me give you an example: I have an order which requires hand delivery and I don't need to generate labels. Moreover, there is nowhere mentioned on the App store that the charges are for orders synced not for labels.

Apart from this hidden charging information, the features are good.

Change in review from 5stars to 3stars:

I think they are average considering most of basic requirements are fulfilled using their app. But unfortunately, we have noticed recently that they are not relevant once your business start scaling up. Hence good for starters with low order volume.

Old review:

Awesome !!
A Perfect Application. It reduces my execution time and multiple efforts while processing orders.

thanks