June 17 2015.
Browsers are quickly implementing ES6 support. However, it's still possible to use transpilers to compile ES 6 code to environments that don't suppotr ES 6. A transpiler is basically a source to source compiler.
Several important language features previously required third party libraries, but ES6 now supports these.
Code written in ES6 is furthermore cleaner and easier to maintain and developers coming from other languages will get comfortable in them.