They are fine for the basic case, but start to fail pretty badly if you do anything complicated. So far we have had problems with: Editing Orders, if you have an app that edit orders on shopify after the fact like a Post Purchase Promotion app send owl will fail to pick it up and not send it out to your customers Partial Refunds: if you give a partial refund to your user send owl sees that as a refund on the whole order and cancels the digital order. Their support is ok and getting back but in the end not very helpful. If you are bootstrapping something simple this is the app for you, but I would suggest against this app if you are dealing with 1000+ customers.

If you want to add subscriptions to your shopify you will need to be able to understand coding. I contacted help desk and they couldn't help me so I just used the paypal subscription button. Works so much easier

It looks good but it doesn't allow multiple file download.

The support was for me a horrible experience. Never had the correct answers to my questions.
Moreover if you have apps like receiptful already installed this will be complicated to setup.