Seems promising as a hobby script, but not for popular consumption yet. I tested the free version and found: a clunky interface that provides no feedback (is something magic about to happen or is it just broken?); suspicious permissions (why is the external service required?). I have a (parent) folder, with several folders with images inside it. On first try I was able to add four images from one folder but when I tried to add some from a different folder it just showed the spinner. I uninstalled and reinstalled then pointed to the parent folder (you can't search for it, because the app shows the contents, you have to "browse" with the UI) and it worked.