I have watched a couple of videos on YouTube talking about Elm. It is a language used to develop user interfaces. It has a very organized ecosystem (unlike JS) and it is pretty cool to code with. Static typing, everything is immutable, etc...

For those who have worked with it, is it worth learning? I would love to know your experience.

Yes, definitely. I've only built toy applications with it (not a web dev, I just wanted something functional-ish) but it was a pretty pleasant experience. I like that it has static typing, predictable logic and a nice clean abstraction over the messiness of JS.

Unlike PureScript Elm doesn't throw monads and stuff at you, it's more like F# than Haskell.