1.Code Snippets panel
Reduce the ActionScript 3.0 learning curve and enable greater creativity by injecting prebuilt code into projects.
2.Creative Suite integration
Enhance productivity when using Adobe Creative Suite components such as Adobe Photoshop, Illustrator, InDesign, and Flash Builder
3.XML-based FLA source files
Manage and modify projects using source control systems and collaborate on files more easily.
4.Wide content distribution
Publish content virtually anywhere, using Adobe AIR for desktop applications and mobile platforms including the iPhone, or Adobe Flash Player for browser-based experiences.
5.Flash Builder integration
Use Flash Builder as your primary ActionScript editor for Flash Professional projects.
Streamline video processes with on-stage video scrubbing and a new cue points property inspector.
7.Spring for Bones
Create more realistic inverse kinematic effects with new motion attributes added to the Bones tool.
8.Deco drawing tools
Add advanced animation effects with a new comprehensive set of brushes for the Deco tool.
if you like to know more details about it, read here. http://www.adobe.com/products/flash/whatsnew/