What is it, what can it do?
To quote Google, “Flutter is Google’s mobile UI framework for crafting high-quality native interfaces on iOS and Android in record time.”
It’s an app dev SDK that targets both Android and iOS (but not web), so you can write an app once (in Dart, not Java or Swift), and deploy on both platforms.
What can’t it do yet?
Can it handle Android’s Activity Lifecycle? In none of the videos I watched was the device rotated; something you have to come to grips with early on when coding for Android. It appears that there are problems saving/restoring instance state, and are actively being addressed.
Unit testing looks to be OK. What about instrumentation tests (Espresso)? Googling didn’t bring much up, except that the example Gallery app does have instrumentation tests, written in Java!
Leave it on the back burner for 6-12 months, and come back for another look.