Kotlin has become my main choice for almost every Java project I have at school, but I think a great language such as Kotlin can be even greater if you can change its syntax a bit.
What I do not like about Kotlin is the For Loop. It should be better to remove the parentheses like in Swift. In the old Java, I feel comfortable with the parentheses since the C-style for-loop in java is a lot more powerful. The for-loop in Kotlin is, on the other hand, just too plain and simple to put in brackets.
Not in this topic, but I think that Kotlin compilation time is not bad. You should pay a bit more attention to the execution time. Kotlin bytecode seems ‘significantly slower than Java bytecode’ for even simple program like for loop a billion times (If you subtract the fix ‘additional constant time’, I do not know how to call it)
Thank you for creating Kotlin.