I was going to add my comments to this list, but I believe that other have sufficiently addressed the concerns and questions raised here.
I find it interesting that persons are lashing out at Anders and how MS are are spending their time and pointing out that there are efforts like Dart and CoffeeScript that are suitable ... well, if you read Mary Joe's article, you'd realize that this isn't really Anders' project (http://www.zdnet.com/who-built-microsoft-typescript-and-why-7000005206/) and also, these guys are language designers, day in day out the think about creating better languages.
Statically typing and type inferencing allow for design time verification have clear advantages ... all developers know this. It seems that TypeScript set out to help bring these advantages to developers *today8 while still doing a number of other things correctly ...
3. They've Open Sourced the thing .. use it, change it, contribute ... whatever you like.
4. They've added awesome tooling support to existing tools like VS that compiles on the fly in the background for users
I'm really happy with what I see so far from TypeScrip. I'm going to continue to use it, get to team to use it and benefit as much as we can the additional productivity that we get from the tools.