Clock says 15:38. Go to time settings. Turn off network time. Turn it back on. Wait for 10 seconds or so.. time updates to correct time and says 16:38. (either Cinnamon loses track of ntp when disconnected/reconnected to network, or it fails to use it at login time)
System: crashes/freezes due to /run/user/<uid>/dconf/user being owned by root (upstream bug in systemd, affects all distributions. The decision was taken not to hack XDG_RUNTIME_DIR and not to hack /etc/pam.d.. i.e. bringing back xdg_support.so in replacement to systemd.so as it could create further regressions with systemd)
Cinnamon: Launching keepass + xsel freezes Cinnamon [wrouesnel] (unknown cause/solution, could be related to XDG_RUNTIME_DIR bug)
System: gksu covers cinnamon panel and clutter layer (offending code is in libgksu, won't fix, likely to migrate to pkexec instead)
System: Support for Wacom tablet (configurable via the command line, will need to join forces with Xfce/MATE if we want to develop a cross DE UI. This doesn't justify pulling resources to make a Cinnamon specific solution)
System: EFI booth path isn't standard (EFI installation in Virtualbox works fine, but upon reboot it loses its NVRAM and isn't able to find the EFI boot files)
MDM: l10n doesn't cover new features (MDM 1.4 is still using the l10n it inherited from GDM. Decision was taken to migrate MDM entirely to Mint/LP translations in 1.6, not just mdmwebkit/mdmsetup).