The 10.9.2 update was the patch that offered a number of security related fixes to address a number of issues like the SSL security flaw, erratic Mail behavior, SMB2 reliability and others. In addition the update added FaceTime Audio only calling and iMessage user blocking which was apparently a very much requested feature.
Apple has yet to officially reply to the AirPlay issues, but some digging and testing seems to indicate that the issue might be more centered around older Macs than the newer ones. Of course that might only be speculation at this point.
So if you happen to own an older Mac and you use the AirPlay functionality, know that you are likely to lose it if you update to the 10.9.2 release. However, if you have a choice between AirPlay and security, we would always tell you to go with security.