My experience is that most Kotlin features boil down to myths created by good marketing. When you look at them in detail they're full of gotchas and unexpected

My experience is that most Kotlin features boil down to myths created by good marketing. When you look at them in detail they're full of gotchas and unexpected behavior (especially when interacting) due to everything being some ad-hoc special case only created to simulate some Scala feature. Tones of ad-hoc features isn't good language design imho, even the features are desirable in isolation. That's the same issue as the biggest problem with PHP or C++. On the other hand side Scala may seem "complicated" on the surface but it's actually just a bunch of quite simple basic principles, and some syntax sugar on top. Scala is like math: It's build form simple first principles. Just it offers the means to combine those and create this way almost arbitrary complex abstractions.