I installed it, it works, it eliminated two other tools I used to use separately (not as easily) and it has become a completely transparent part of my workflow, I don't even know I'm using it anymore. It's one of the first things I install on a new Mac.
The best $5 I ever spent. It's now $8, but still worth it. I have TONS of ideas for v2. If you sit on video conference calls with slides being shared, this is a dream for capturing information you can use in your daily duties.