"There are very few programmers who know how to use the language effectively" - Douglas Crockford
ES6 and ES7 are going in the right direction to improve mantainability (e.g. modules, classes, improved async programming, arrow functions, promises). When you combine those features with a type-system, it is great material for faster runtime environments and optimized JIT compilers execution. The predictability of types will fit very well into the hidden class system used by most engines, and make the JIT compilers much more efficient at caching, which is the key to performance. The already fast Google V8 engine will be more like a V16 engine in the future!
I know there are other ways to use future JS features (e.g. Harmony shims etc.) but their API's are less stable than TypeScript. Here is a comprehensive list of all the options available:
What is TypeScript?
TypeScript is something like a time-machine that allows you to use most future ES features right now, in all browsers. It does not follow the EcmaScript specification 100%, so there are some features that differ from the future ES specifications, but it compiles into 100% compatible ES5 code.
It is ready to use in .NET, Node.js, Angular or any other framework or library you might be using. It is proven in production and big applications have already been built with it (e.g. Microsoft Azure portal).
The TypeScript site has a nice playground where you can experiment with TypeScript directly in the browser and see how it works:
What does the TypeScript compiler do?
The compiler itself is a command-line application with a simple API that you can run on any platform. It is also integrated in IDE's (e.g. Visual Studio) and text editors (Sublime Plugins). You can also easily run it in your CI/CD pipeline.
How can i move my existing JS to TypeScript?
How do i know that my investment in learning TypeScript will pay off?
TypeScript is a tiny investment, since you can still use all existing JS features, so it's not a big risk at all to invest time and money in TypeScript.
In addition the big players are gathering around TypeScript, which proves it worth. Microsoft (the inventor of TypeScript) and Google (Baking TS into Angular 2.0 by default) are two biggest supporters of TypeScript right now.
In addition, TypeScript will always be one step ahead of the current EcmaScript implementation, so even after ES6 gets out in the wild, TypeScript will still be a good idea, since it will be a superset of ES6 implementing ES7 features.
TypeScript is a good idea. For C# and Java developers it will feel right from the start, because of the strong OOP approach. Ruby and Python programmers will still prefer CoffeeScript, but eventually many will recognize the benefits of TypeScript.
When Angular 2.0 comes out later this year, TypeScript will become the mainstream, so get on board as soon as you can!