This is dead useful. I have told the developer to make how to use it a bit clearer on the "About this Extension." It should state where the add-on appears in a Jira ticket. It's unobtrusive in the Jira view and where it is placed.

You get to pick the versions to compare, it shows them next to each other with differences highlighted.

This extension is okay I guess. I can now see my Jira diffs with ease. My PM always tried to sneak in a few acceptance criteria and pretend they'd been there the whole time. Not anymore... I see you.