React-Native.

Worst process to upgrade to a newer version ever. Plus error messages are mostly useless

Ive heard a lot of good things about react - native. I personally haven't tried it but I'm glad I'm hearing something negative about it as it sounds too good to be true!!

I kind of agree. But if you know it then everything becomes so easier.. can't accept react native as worst dev tech.

I develop mobile apps since 2011. There isn't a language/tool/framework out there meant for mobile apps that I haven't used.
React Native is the hype of the time but is also one of the first tools that does what is promising. It is catching up very fast but is still not there.

BUT

It is horrible to upgrade, I have many concerns about security, I've seen ridiculous bugs & error messages and given that it comes from FB documentation is not the best.

Still one of the 2 best options to build a cross platform app.

In 2017 native is still king. Maybe it would be king in 2018 as well. Eventually this will not be true and it is possible React Native will win.