There are only fixes in 12.1 RU2 MP1, no new features.
Release notes are here
http://www.symantec.com/docs/DOC6419
Fix notes are here
http://www.symantec.com/docs/TECH204685
You should also be aware that a bug has been found in this version that affects XP/2003 clients if the firewall is enabled. SMB traffic is severly degraded. See thread here
https://www-secure.symantec.com/connect/forums/slow-network-after-upgrading-endpoint-protection-1212-mp1from-previous-version
Unless one of the fixes addresses an issue you may be having, I would hold off upgrading.