In my case, transitioning from the editors in Turbo Pascal and Turbo C was very straightforward. Their key functions were also based on those from WordStar.
This was back in 1995. And I'm still using joe as my editor for anything from config files, through html/php to C. Just as many other people have said, it's the first package I install on a non-Slackware environment.
Since I worked at a University, and had a team of young and impressionable students working with me, there's a whole generation of joe-addicted slackers here in Costa Rica.