Borrowing the short description from the TypeScript project:
New features available in TypeScript are not all just some additional sugary syntax. The TypeScript language is attempting to follow the ECMAScript Harmony (6th Edition) spec for most of these new language constructions. Although the standard is not complete, Microsoft has said that it aims to align TypeScript’s features with the proposed standard. This gives me some assurances that TypeScript will succeed because it is following the Harmony specification that future web browsers will certainly support.
And this editor capability is not limited to Microsoft Product. Jetbrains has already included TypeScript support for WebStorm 6.
I wish I had more space to show all the features the language provides in one post. If you want to follow more of my observations with TypeScript, I have started a series over on my personal site. You can also read the sites below for more information on the language.