React is pretty mature and time-tested and it has been the most used web framework/library by developers over the years. Its main goal is to be extensive, fast, declarative, flexible, and simple. React has been designed from the start for gradual adoption, and you can use as little or as much React as you need.
React is quickly developing, which is both an advantage and a disadvantage as it can be a major challenge for developers to constantly relearn how to use it.
Unlike its major competitors Angular or Vue, React is not a framework but a library that focuses only on the UI layers of the app. One still needs to choose some other technologies to get a complete tooling set for development in the project.
Finally, React doesn't impose any development conventions. This gives a lot of freedom for developers but at the same time it may take longer to introduce new developers to an existing project because very often developers create React apps in different ways. It requires extra efforts for efficiently structuring code in a unified manner.
Cegal and React
Cegal has many consultants specializing in frontend development, including experience with React.