User blog comment:DaNASCAT/Technical Update: August 22, 2016/@comment-452-20160824225437/@comment-126761-20160825135341

We're aware that the 'nice work!' option reappears when you refresh a page - but clicking it again does not send a notification twice. Additionally, we know that the 'Hide page content below diffs' preference hides the option on diff pages.

If you've spotted other issues, do let us know via Special:Contact/bug. This is a test feature so some rough edges are expected, but but we want to minimise that of course.

Behaviour around anons is definitely an open question. I think that time-sensitivity would probably be the major consideration there: IP 'usefulness' can expire quickly, so you'd likely want to make sure any thanks given or received are pretty close to the relevant edit.