Performance is roughly the same and you have access to most of the platform features that most apps need.
I messed around with a few cross platform tools a bit and my impression is that if you want to make something that is better than a WebApp you actually have to learn a lot more tools and frameworks and everything feels like falling apart and you are depended on multiple vendors to upkeep the tooling.
The moment you say that your app is more than an UI to access a database, native on multiple platforms is actually easier.
That's a lot of extra complexity, but it's also no less than if you had built two native apps. You're now just expecting a single team to manage it.
My background is in "real" native development (both Android and iOS) so I get on fairly well with this, however, for people coming to React Native from the web side of things, it's a lot to take in.
Overall, I still recommend to 90% of my clients that React Native is a good way to go if they have limited time and budget. For larger companies, they might have the budget to build and maintain two apps.
Also, most apps really are just UIs on top of a REST API. And even if you do want to make something more custom, you can always create a native component or module yourself for each platform and wrap it to use it with the rest of your React Native app. That way the "boring bits" like the account management, data handling, etc can all still be shared.
It's a trade off, but just about works out for me.
RN, never again.