The new features include:
- Live Edit Mode – Preview of your app in Google Chrome
- JSDoc annotations of Google Closure Compiler supported
- Jade templates support
- Project-level JS libraries
- Debugging support for JSTestDriver tests
- Improvements for Sass/SCSS
Every change to the source files is automatically visible in the browser. When you click on a html tag in your sourcecode, the corresponding element in the browser gets highlighted.
Live Edit Mode will definitly boost developer productivity. You should use two monitors to enjoy this feature.
Regarding the JSDoc annotations support of Google Closure Compiler:
With these annotations you can define types, interfaces (and implementations of interfaces), private and public variables, inheritance, enums etc.