The list of new feature is huge. The first improvement but for me not interesting at all is windows vista native support (double-buffered painting, WPF).
Here is my filtered list 
- Ctrl + 3 -> quick access UI elements (views, commands, preference pages..) with initials of words searching.
- Ctrl + Alt +Click -> step into method when debugging
- Refractoring without dialog
- Initial searching – GS finds GenericServlet
- DateTime control
- Show references/all instances when debugging on java6
- Null variable check detection improvements
- Content assist for variable with unresolved type
- Great mozilla integration
- Open multiple types
- Annotation processing
- Comparing/patching improvements
- SSH2
- Quick assists now support also refractoring part
- Spell checking
- Content assist in plugin.xml and MANIFEST.MF
- Scrolling Ctrl + mouse wheel
- OSGi R4.1
- Undo operation – undo’s resource operation and task and bookmar