The latest release candidate includes a series of bug fixes, that are detailed on Adobe's blog site, in addition to support for 16, 24 and 32-bit HDR TIFF files.
The most interesting update, from our perspective, is the improved
ability to remove the purple and green axial CA that can appear on
out-of-focus regions, particularly those shot with fast lenses. Adobe's
Eric Chan explains the feature in a detailed blog post.
As usual, the Release Candidate tag indicates 'that this update is
well tested but would benefit from additional community testing before
it is distributed automatically to all of our customers.'