Thanks for asking this question. I'm also a Rails dev, pretty much in the same situation. Some people are mentioning that if you want to do some server side rendering then things can get a bit more hairy.

Well I don't want my backend app to be just an API and the frontend to be a client. I'm not trying to argue whether or not that is the correct way to build web apps, but I don't want to do all the rendering on the frontend. The reason is that I think this would make smaller projects a good deal more complex. Maybe you can convince me I'm wrong. Again, I can imagine that if you are a big company this might be the way to go. But for building small to medium web apps I think Rails (and the Rails way of building apps) works well. What I'm trying to figure out is if I can incorporate React into my toolbelt and have it work well with standard rails apps.

Apologies for my grammar.