I'm a react native consultant, so I've seen several different projects (of all different sizes). Overall, I've been super happy with React Native, and would easily recommend it to anyone looking to build an Android and iOS version of the same app.
There have been a lot of changes since 2015 - and the overall experience has gotten quite a bit better. There are many more modules available for both platforms (in 2015 you probably found a lot of modules only supported iOS and not Android) - and in general the whole ecosystem is more stable.
That said: not everything is perfect. React Native moves quickly, so there are sometimes frustrating bugs (especially in new releases) that can take a bit of time to resolve. Also, it's not a great fit for every type of app. 3D games are an obvious example of when you'd want to go native (or use unity).
However, after having done native iOS development and react native development, I can say that react native is still faster (development speed). In practice I find that I can reuse 95% of the code between iOS and Android, so it's been a great win for the teams I've been on.