If you have a Linux or Mac handy, you can trying it out! It's...kinda wild. If you know some Vim commands that start with :, there's a good chance they'll work in ed, except you don't type : itself (effectively you're always in "command mode").

There's also a novelty Twitter account, @ed1conf, that tweets about ed.

Some coworkers told me a story about a previous job candidate who said his preferred editor was ed. They thought it would be really interesting to see someone actually use it. But during the actual interview, when he opened ed, he didn't recognize or understand it; he was actually accustomed to a graphical editor that he thought was called ed because he apparently did all his work on a system where someone had symlinked or aliased ed to a modern tool.