The key areas addressed include:
* Upgrading Aperture 1.x and 2.x libraries
* Importing libraries from iPhoto or from earlier versions of Aperture
* Importing hierarchical folders of photos into a library
* Adding names and confirming matches in Faces
* Reordering snapshots on the Faces corkboard
* Creating and saving print presets
* Duplicating metadata presets
* Adjustments using Curves, Straighten and Retouching
* Navigation of photos in the Viewer using scrolling
* Importing ratings, color labels and GPS data from XMP sidecar files
* IPTC metadata compatibility
* Deleting photos when emptying the Aperture Trash
* Exporting versions and libraries
* The update is recommended for all users of Aperture 3.
Read more about the update here.