Read "Thanks" section in http://redux.js.org/ I knew Elm long before Redux. When I saw Redux the first time I was thinking that we finally get Elm in plain JavaScript now. You may find several Redux feature already in Elm:
And code in Elm looks quite neat:
https://github.com/evancz/elm-todomvc github.com/evancz/elm-todomvc/blob/master/Todo.elm
So in Redux there's a single store with a pure updater to finish transformation among states. By introducing "single store" it became easier to realize consistency of data. By using immutable data and pure functional programming it made time travel debugging easy to implement. And that resulted in a very brilliant solution for developing web apps. So it's definitely worth learning.
I will also suggest learning Elm because of the messy ES6 features that made Redux look heavy.