It adds new effects, includes improvements and fixes
The stable version for Audacity 2.0.3 is close to getting released, as the development team rolled out the first RC over the weekend.It brings to the table new effects and plenty of bug fixes and improvements. The current revision does away with a couple of crash bugs; one of them occurred when using “Undo” command while time-shifting a track, while the other terminated the application when using the “Repair” function and the selection extended into an empty track.
The list of effects has grown and now includes entries such as Studio Fade Out (uses a filtered "S" curve), Adjustable Fade (creates partial fades and adjustable fade shapes). Also new is Bass and Treble, but it replaces Bass Boost.
For a full list of modifications, you can consult this page.