This looks like it could be a really great tool. I was excited to try it, but unfortunately the app is pretty unusable for me on Ubuntu. It has been frequently crashing with "an unhandled error has occured". When it's not crashing, it seems to be running at 5-10 FPS. It also seems to be hogging CPU, with some WebKit process running at 250+% CPU.
This is just a preview, so I'm hopeful the developers can work these issues out. Judging by their website, I could see this being a useful tool!