Like for everything else, the horrors of ReactJS are seen when:

• you use it and do not need it
• you use it but very naively

As for the biggest limitations: I can't answer that question, I have not met significant limitations in the way I use React. It doesn't mean it is perfect, and there are other projects solving similar problems more elegantly.

React is not a framework, there is a very wide ecosystem around it. You can write applications where React only plays a small role (taking care of the view), and therefore can hardly become the limiting factor.

Here are some of the horrors of reactjs -

The learning curve involved with it

There is a lot of tooling and configuration required for getting a simple app running.

• What to use? Webpack or gulp/browserify?
• How to mix ES6?
• What is virtual dom and component lifecycles?

JSX

While its not really a horror but wrapping head around it and writing components is tricky and is not as simple as pure HTML and JS. It looks like you are mixing HTML and Javascript when working with JSX.

Thats all, I can think of. Most of which is related to learning. I havn't encountered anything particularly bad in React so far in terms of a frustrating pattern or bad design.

I am looking forward to other answers to this post. :)