The compile time guarantees could have been much better, especially around null pointers. Now they're hacking in non-nullability the same broken way they did it in Java. Same goes for a lot of things like switch / case statements requiring breaks but not supporting checks for covering all cases compile time.

In general it just feels like old Java spiced up with some Javascript niceties like Futures and a nice constructor syntax.

But you should've noticed that coming from Kotlin?

Why wouldn't they use Kotlin as most mobile developers are already used to it?