I've just installed Linux Mint 13RC, which is based on Ubuntu 12.04. The only problem I've found (so far -- knock on wood) is not with 13RC but with an application in it: viz., Alarm-Clock-Applet, http://alarm-clock.pseudoberries.com, which is available through Synaptic and the Software Center.

This is an applet on which I depend heavily to manage my sessions at my desktop. It has worked perfectly for me in Linux Mint 11 (based on Ubuntu 11.04), but in LM13 the alert sounds are played only once, whether or not I select the "Repeat sound" option in the applet. The difference is that LM11 uses v. 0.3.1 of the applet, and LM13 uses version 0.3.2.

It turns out that this new (and latest) version of Alarm-Clock-Applet has a bug in it: the failure to repeat the alert sounds. The bug is known to the developer, Johannes Jensen. He has offered a work-around in https://bugs.launchpad.net/ubuntu/+s...0?comments=all

The work-around involves changing the format of the alert sounds the user wants to use, from OGG to WAV. However, the names of the files must remain unchanged. The files to be changed are located in the following directory: /usr/share/sounds/gnome/default/alerts/