Especially for Android, native components does help a lot, and it does feel like you have direct access to everything. React itself is also a lot less opinionated than Android and gives you more freedom. Try their demo app Ziliun Reader from Google Play and compare with ionic starter app and you will see what I mean.
Really torn about the two frameworks. With React Native you have access to native components, you will have to maintain two code bases as a result. Ionic is based on Angular which is much more popular than React today however . . . so torn . . .