The most useful thing about A2B is being able to know where in our organization one product or item has been at any point during its journey from creation to delivery.
It's also great if something goes wrong with your shipment, for example, that it can be tracked back to the exact location so we can find out exactly what went wrong (if anything). I think there are some features missing but they should be added soon enough - like better integration between different departments within the same company. We use this software as part of our work flow by tracking products from origin all the way to the customer.