This is a good free app. A couple of things to consider:
If you're just selling digital goods on their own, this app automatically fulfills the order by default (sending the customer a download link). Which is good.
If you sell a product that is both physical and digital (for example I sell a physical poster, with an accompanying downloadable PDF) by default the app will fulfill this order (or at least the line item in question). This means your order doesn't show up in your list of open orders, so you wouldn't know that there is a physical item that needs dispatching (without relying on being vigilant). To counter this, you can change the settings on the digital attachment to 'manual fulfillment', which stops this. However, if you do this, the digital download link only gets sent to your customer once you've dispatched the physical product (or marked that line item as fulfilled). So if you receive an order on a Friday and don't ship it til Monday, your customer will only receive the download link on the Monday, which isn't great.
To make this app 5*, it needs a 3rd setting which automatically fulfills the digital items (sends download links to customer straight away) but also leaves the physical item unfulfilled, so that you can follow your usual dispatch process.