I've used it for multiple apps at this point and it's been a huge win for me in terms of productivity (I'm also quite enjoying Reagent with ClojureScript so far, but I'll withhold judgement on that for now). Trying to apply simple FRP-style abstractions over state changes like Signals becomes infinitely more tractable in React, where components are just functions that return data (as opposed to most frameworks, like Angular, with their very effectful controllers and other code).

Also, having worked with both Angular and React alongside less experienced developers, I've noticed developers in general doing a lot less stupid shit with React (not to say none, just less). Angular doesn't have many strong philosophies about programming, so it's largely up to the programmer to make good decisions rather than have the framework make the right thing feel right - the latter, in my opinion, being what growing developers need.

My sample sizes have been limited though, so take this advice with a grain of salt. Also, I picked on Angular because that's the other framework I have a reasonable level of experience with, but you could substitute most frameworks in its place.

EDIT: One thing I'm still missing is Flux. I tend to use React alongside PouchDB, and thus haven't really encountered a need for Flux, but even then - I think I simply don't get it. I mean, it's just a convoluted event bus, right? What's the big deal? I don't mean to undermine the efforts of Facebook's engineering team(s), I rather feel like there must be something about the Flux architecture that I'm missing, that somehow makes it more valuable than a simple event bus.