Same, we're using Flow in for our React Native app but not yet in our older webapp.
I've found more bugs that way that more than offset the extra time spent writing types and being a little bit more verbose to keep flow happy.
The minor annoyances are around the edge cases. Like eslint/flow throws propType errors when using props that were dereferenced from `this.props.someObject`. But you can just write the longer version `this.props.someObject.whatever` and everything's fine.
I've found more bugs that way that more than offset the extra time spent writing types and being a little bit more verbose to keep flow happy.
The minor annoyances are around the edge cases. Like eslint/flow throws propType errors when using props that were dereferenced from `this.props.someObject`. But you can just write the longer version `this.props.someObject.whatever` and everything's fine.