You seem to have plenty of screenshots, but I don't find them to be particularly informative. After reading through the page and glancing at all of the images, here's what I take away: it's a tool that allows you to enter a pull request URL and display a side-by-side diff.
The side-by-side diff feature is buried at the bottom, and the whole page seems to imply that there are other features within somewhere, but I can't figure out what they would be (I would love to see screenshots of them!).