With regards to your comment about performance, I personally think it feels snappier than FB3. I have actually been using it for quite a while, and am really liking the small things, e.g.:
- Abbreviated type and variable lookup: Typing
TFAS will auto-complete TextFieldAutoSize. Same goes for hEF, which will auto-complete handleEnterFrame() (if you have created such a method.)
- Vector auto-completion: If
myVector is a Vector.<DisplayObject>, typing for example myVector[0].tra will now complete myVector[0].transform.
- Cmd/Ctrl + O will open an outline view similar to FDT's quick outline. The abbreviated lookup works in this view as well.
And of course, the bigger stuff includes improved navigator panel/package explorer, profiler and Flash CS5 integration.