Yep, I switched over to that when it hit -rc1 (Linux mostly, but I also tried it in Windows).
Subtle improvements to the user interface (e.g. less stealing focus, ability to save tool options and/or revert them to defaults).
New and improved tools and filters.
Better controls when saving images, especially jpegs.
Better control over selections. For example, the rectangular and elliptical selections are now adjustable after a selection is made. (If you stuff up a free hand selection you still pretty much have to start over though).
The program is now SMP aware (and has a setting to specify the number of processors to use). Not that it would matter for just every day photo editing, but if doing transformations to large images it would certainly help.
I'm sure that's not all, it's just the things I've noticed in my usage of the program.
