The language is easy. One can also learn English in 5 minutes: SUBJ-VERB-[JJ]*-OBJ, done! The library ecosystem and best practices on the other hand...
Agreed. I love Typescript and picking up Dart has been quiet easy. Of course there's much more than the language itself, but other than one detail or another, tha transition seems to be fairly easy.
You can honestly pick it up in a weekend, there's nothing particularly new or groundbreaking.