I found the transition from Java to Kotlin painless because Android Studio (Intellij) holds your hand all the way. If at first you're unsure of the syntax, you can just write code in Java and convert to Kotlin.
I agree that the null-safety Java interoperability does not work properly if the Java code is not annotated correctly (or you're parsing JSON) but I'd still prefer to have it than not.
I like Kotlin because:
* If is an expression and it feels so clean
* Functions are first-class (you can pass functions to functions)
* Kotlin is less verbose than Java so there is less to read and write
* You don't have to write "new"
* Constructors are cleaner (you don't have to write (this.a = a)
* The map function (on Android we were stuck on Java 7)
I agree that the null-safety Java interoperability does not work properly if the Java code is not annotated correctly (or you're parsing JSON) but I'd still prefer to have it than not.
I like Kotlin because: * If is an expression and it feels so clean * Functions are first-class (you can pass functions to functions) * Kotlin is less verbose than Java so there is less to read and write * You don't have to write "new" * Constructors are cleaner (you don't have to write (this.a = a) * The map function (on Android we were stuck on Java 7)