Nice to see it mentioned here :) I am currently using it as a "helper application" to perform certain tasks such as health checks of my projects and automating several GitHub actions. I have wrote several blog posts about it:
- simple health check: https://dev.to/krusenas/creating-your-own-health-check-monit...
- regenerating brew formula hash on update: https://dev.to/krusenas/automating-github-tasks-with-node-re...
While these things are trivial to do in my preferred languages (Golang, Python or Javascript), doing it in Node-RED is kinda fun.. :) Very easy to experiment, extend and do pretty much anything you want. You can always use a "function" node to just write some custom javascript logic if you see that you can't find a suitable node out-of-the-box.
All in all, I think Node-RED really shines when it comes to home automation. Comparing it to alternatives such as Home Assistant, Homeseer or Domoticz, it's a lot easier to understand what is happening and why. Of course, there's less magic involved here and it might make things a bit more difficult for non-developers, but the end result is definitely more stable and better long-term.