I am mostly using it for hobby projects by now, but for me it is the very transparent yet mighty type system in addition to the aforementioned aspects. Its macro system is a sweet spot in comparison Ruby’s metaprogramming, which can easily be taken way too far. Also, if you do it right, you can build containers from scratch that are small in size and boot really fast. It has a really well curated and extensive standard library that lets you get away with including a lot less dependencies. It comes with a linter, a test runner, docs generator and quite useful debugging features.

I am looking forward to what AI can do to port Ruby gems to the ecosystem.