@mhartington: is there a reason you recommend going straight to the --ambient flag? I consider it a last resort, because if you can install without it, you know you are using a tsd that has been vetted by the typings registry and get some extra versioning and namespace pollution protection.
I was referring more to your blog post giving generalized advice, which would have people install from DT even for libraries that are in the typings registry (which is growing fairly quickly).