For information on the security updates see Security Bulletin APSB13-02 for details.
For detailed Release Notes, please see the Enterprise Toolkit.

A few highlights to be aware of:

New Updater Mode Added to Acrobat XI for Windows
The Adobe Acrobat XI for Windows updater now has a fully-automated mode. As a reminder, “fully-automated” mode will regularly check for important updates, download them to your machine, and install them automatically. When finished, you will be alerted via a small message in the system tray that your software has been updated. This method is the recommended best practice for keeping Adobe Acrobat up-to-date and more secure given the fact that it does not require user intervention.

Handling Flash in 10.1.5
As mentioned in Three Common Adobe Reader and Acrobat Security Questions, unknown Flash will now be rendered by the system Flash Player (NPAPI version), when using Adobe Reader and Acrobat 10.1.5. Note: This has already been done for Reader and Acrobat 11. As stated before, this means that Adobe Reader/Acrobat users will no longer have to update Adobe Reader/Acrobat each time we update the Flash Player. This is particularly beneficial to customers in managed environments, because fewer updates means a lower cost of ownership, while maintaining a vigilant security posture.

And as a reminder, support for Adobe Acrobat 9.x will end on June 26, 2013.