I have worked with Redux as well, and write functional JS pretty much exclusively, and agree that it's actually very pleasant to work with these days, especiall

I have worked with Redux as well, and write functional JS pretty much exclusively, and agree that it's actually very pleasant to work with these days, especially if you're also in an environment where you can take advantage newer language features like async/await. My #1 pain point with functional JS though, is that using a persistent data structure library like ImmutableJS or Mori removes the ability to use some of the awesome new syntactic sugar introduced in ES6 like the spread operator, destructuring, etc, for making code less verbose. So you have to make that tradeoff between being able to use a succinct syntax for common operations vs having the optimal performance in terms of memory efficiency and garbage collection pressure. I'd really love to see native persistent data structures as a first class citizen in JS so they can make use of all new language features. Until then, I'll probably continue to choose ClojureScript for my own projects.