I really wish it was open-source. I loved the concept and the app worked in most applications (though not the best with Slack). But I have reservations when it comes to granting full screen access to an app made by some unknown developer.
I feel the same, so I simply block its network access (via LuLu), and it works just fine that way. I wish it was open source so I could hack on it and so development could continue - it's a really cool idea and works pretty well.