Having used both Flux and Redux for fairly large projects for the past two years, I have finally come to the conclusion that I really don't need either. I tried to summarize my alternative here, although I'm sure many will disagree:
As goes with every extra dependency: don't use it until you actually need it.
I will say that using it by itself is probably going to be challenging. You'll want to use a connector library (like react-redux in this case), invest in some good API middleware, etc.
Maybe it works on large teams and code bases, but it is unnecessary on smaller teams where sane code practices are enough.
It's remarkable to me that real clients like Relay haven't caught on as much while Redux wastes so many peoples' time.