I really like the idea. A visual story board of your script or screenplay... so that you actually get to see the big picture in a flowing way. Adds great value.
But I agree... the annual subscription is a bad idea, this is the wrong approach. And the purchase price is way too high. As $39 or even $49 software, I think you'd have a hit. But $149 is just too much. I'm a real software and app geek... but hey, just my opinion.