I'm on mobile and currently I am unaware if there's a way to see who reacted how without pressing on the emoji and adding myself as someone who reacted in the same way.

Also, it doesn't seem to work like upvotes where you can press it again to remove it.

And holding a long press brings up the list of reactors, but it remains on screen in a persistent fashion.

Are these common issues for an average user or is the feature still in development?

All of PieFed is still in development :)

Thanks for that! You folks rock!

In general, the popups don't work great on mobile. We have them on lots of other UI elements (like navbar buttons in the upper right on desktop) and they are a native Bootstrap thing (the css framework we use). However, they aren't really touch friendly, and seem to get stuck a lot (even on desktop). If any web dev folks out there know a better solution for this functionality, we are open for suggestions.

It's nice when the things we make keep being improved, little by little.