Definitely interested in seeing how Flutter progresses, IMO it has the optimal architecture for developing native, x-plat iOS/Android UI (https://flutter.io/technical-overview/):

   - High perf Skia based UI for pixel perfect rendering and high-level Material design widgets
   - React inspired, productive development model
   - Fast dev/iteration cycles with hot reloading
   - Productive and high-performance Dart language, natively compiled (AOT on iOS)
   - Enable native interop with underlying iOS/Android APIs
   - Actively developed by Google

Overall I think it has a superior architecture to React Native where it will enable higher-perf native iOS/Android Apps in a single code-base but still enables a productive development model with Instant UI updates and hot reloading. I've done Java and Kotlin Android Apps as well as Obj-C and Swift iOS Apps but I find React Native's dev model a lot more productive.

Unfortunately I've run into a few issues with React Native that I've had to workaround which I've submitted repros to months ago but received no response from the React Native team except in the last couple of days where they've closed it without even looking at it because it didn't receive comments/activity from other devs. In the last 2 days React Native has closed 773 other issues because they consider it low priority:

https://github.com/facebook/react-native/issues?q=label%3AIc...

This gives me low confidence that React Native will be a high quality platform with current low-priority issues lingering indefinitely so I welcome competition from Google with Flutter and will be anxiously looking forward to trying it out when it gets out of alpha.