A new backup engine. We have redesigned the backup engine's architecture to make it more efficient and more robust.
More checks in ALICE and ANGIE to warn you of more common issues and let you work around them easily.
Interface improvements. We made some aesthetic and functional improvements in several places of the component to make your life easier and improve the way the component looks.
A new Amazon S3 integration. The new integration (Upload to Amazon S3) uses the Amazon PHP SDK for improved compatibility and performance. The old integration (Upload to Amazon S3 (legacy API)) which doesn't support all Amazon S3 regions will be removed in a future version of Akeeba Backup.
Deprecated features. Some features are now marked as deprecated and will be removed in a future version of Akeeba Backup: Site Transfer Wizard, Lite mode, System Restore Points, Extension filters. These features will be gradually removed after January 2015.
...plus several bug fixes and minor improvements.