I am using Eclipse Ganymede for about three months now (since RC5 or RC6) and I am really excited about the new version. Here are my favorite improvements:

1. Performance
   • Java compile on multi-CPU machines – the Eclipse Compiles now takes advantage of multi-threading capabilities of multi-CPU machines. Builds are a lot faster!
2. UI improvements
   • I am a Firefox user so I am happy that it is now possible to close tabs by clicking on them with the middle mouse button
   • Focus on tooltips on mouse over – this means you do not have to press F2 to focus a tooltip. It allows selecting text inside a tooltip just by moving the mouse into it.
     
   • Quickfixes are focused on mouse over too. No double clicking on the small warning icon in front of the code line anymore – just moving the mouse over the wavy line below the bad code and click on the hyperlinked quickfix.
   • Debug tooltips show more detailed information – like in the variable view.
   • Values of constants are shown in tooltips too on mouseover
     
   • Rearranging code elements by drag and drop in the outline
     
3. Coding
   • Code completion helps with casts – it reads the type of the instanceof condition and automatically offers more methods
     
     Afterwards it adds the necessary cast
     
   • Convert to StringBuffer quick assist – is useful sometimes when refactoring bad usage of String concatenation
     
4. Formatting and cleanup
   • Format edited lines only – this setting allows you to format the code you added or changed and leaving the rest of the class untouched
   • The new cleanup settings allow to correct indentation and adding unimplemented methods automatically
   • Undo formatting for a set of Java elements – If you format your whole source or a package it can be undone again
   • Comments are formatted at the same time as code is formatted – happens in one pass and is a lot faster (for big classes)

See the New and Noteworthy for the whole list of new features.

There are a lot of plugins that are released simultaneous in new versions:

• Web Tools Project version 3.0 – now includes a very nice JavaScript editor that allows to format JavaScript code in the same way as it is possible with Java code
• Subversive version 1.0 – the official SVN plugin the Eclipse project chose
• Mylyn 3.0 – no list of changes available until now

Thanks to the Eclipse team for bringing us this exciting new version of such a great tool!