In addition to a number of bug fixes and small improvements, security vulnerabilities have been discovered and fixed. As always, we recommend that you upgrade your sites to these latest versions as soon as possible. All admins of registered Moodle sites have been notified with security issue details.
Upgrading from any release in the same branch should be very straightforward. Full details about these releases can be found in the release notes:
Note that as of this release the 2.2 branch is deprecated and will be supported for security fixes only.