May I ask where you invested your time in learning Scala (e.g. reading the red book, studying type theory, syntax + stdlib + collections, etc.)? I found I could read simple Kotlin in a couple afternoons, and after a couple weekends, I felt pretty comfortable with it. The only difficult concepts to wrap your head around, I'd say, are type safe builders [1] and coroutines [2], but you certainly don't need to know those to be productive in the language.

To answer your specific question, however, if you're doing Android development it's worth it :) otherwise, it's up to you/your specific situation.

[1]: https://kotlinlang.org/docs/reference/type-safe-builders.htm...

[2]: https://kotlinlang.org/docs/reference/coroutines.html

If you're familiar with Java, adopting Kotlin is just a matter of setting it up and reading the docs frequently for a week or so.

If you want to, Kotlin can be practically Java without the over-verbosity and some nice extra features. In time you'll be writing less Java-Kotlin and more Kotlin-Kotlin, if you get what I mean. To me the syntax and structure is so resembling to Java that I haven't really had any confusions at all, most of my gotta-read-the-docs moments involve the concepts that you can use that aren't present in Java (along with the `when` version of `switch` which I've grown to love).