Is there any benefit in learning React Native since I have to write for both Android and iOS platform?
Besides that, there's the incalculable benefit of being able to use the same mental model (to say nothing of programming language) when developing, especially when designing UI components and animations. Even if you had equal skill with building layouts in both systems, there's great advantage in not having to context switch.
The ability to reuse code is very real, even sharing a lot with a web react app since most state/business logic is in some flux implementation.
The pain points (documentation, build process, etc.) are real, too, but things I can forgive for now due to its newness and its very strong foundation.