Update: After using the service for 6 years I can tell you that this is by far the best shipping solution we have found for Shopify. The workflow is simple and intuitive, the user interface is seamless and neat, and the customer service is absolutely wonderful. I don't think we've ever had a major issue with the program, but the Ordoro team was always helpful giving us a rundown of changes after any program updates. We strongly recommend getting an Ordoro Pro account for any business with medium to heavy shipping traffic as the dropshipping and kitting options are great for large inventories. Give Ordoro a shot!!!
This is a great app. It's intuitive and works seamlessly with Shopify. The biggest plus for our company is the stellar customer support. We get help instantaneously; real help, not some bored programmer, but people with their synapses firing who are patient and willing address problems and train our staff.
You want your shipping program to keep inventory and talk to your shopping cart ... so the marriage between the two has to be squabble free. Shopify and Ordoro make a great couple!