[Vinnl]

Interesting. There are downsides to using TypeScript (build chain complexity is the major one for me, although that's getting less and less relevant as more and more tools gain native TypeScript support), but the three you mention are not relevant to me.

- I don't know what unreleased API's you're referring to, but I generally haven't seen the need to use them - if they're unreleased, I try to avoid them.

- Especially for projects with fast iterations, TypeScript has been massively useful. Changing the API around, which I do often at the start of a project, is just so much easier when you've got TypeScript to make most of the required changes, or to tell you where you have to make changes.

- Type availability might be a problem, but I also generally stick to major packages for which it's not. But yes, I have learned to contribute to DefinitelyTyped - which luckily is a relatively smooth process.