Can you say some ways it is more complex than other type systems? I think type systems are inherently complex.

From my perspective, I feel user-facing complexity is quite low in TypeScript in some key ways. You can write your type declarations anywhere, you can import and export them in a familiar JS-module way, you don't need to explicitly type anything in particular so you can be anywhere on the spectrum from very rigorous types to no types at all / `any` everywhere, and finally it has really good error messages so you rarely are stuck with a type mismatch that makes no sense.