I liked the idea of typescript but after frustration from fundamental issues I was very happy to bin it.
i) Wrapper libraries - Sure you can download them from definitelytyped but in practice I quickly found all sort of incompatibilities and things not working when used on real versions of the wrapped libraries. I had to edit them based on suggestions from forums. They are unversioned community efforts - poor versioning and no package manager is just a nightmare given the dozens of libraries we have to use for modern JS.
ii) Tooling - I thought this was the benefit and tried using it from WebStorm which claimed Typescript support. I found no meaningful intellisense only that it shelled out to the TS compiler in the background with some flakey syntax highlighting. The worst issue was that the compiler could regularly produce totally opaque error messages that were poorly located to the code issue and probably in the wrapper somewhere.
iii) Arbitrary apis - this is what I thought I wouldn't face but it was. Just a single line of code trying to the most basic task of creating an express server took hours of googling for the magic incantation. Most advice referred to the wrong version. It appears there are javascript patterns that typescript wrappers struggle to represent so the authors have to invent new ways of offering an interface. Wrappers don't come with documentation... even if they did, you now have to read both the original and the wrapper documentation. Not cool.
I hope some of this is now fixed but to have unreliable wrappers, no versioning and bad error messages means I am not hurrying back anytime soon.