Should be more stable than the latest nightlies
The third batch of 'M snapshot' builds for CyanogenMod 10.1 are starting to roll off the servers today. The 'M' builds of the Android 4.2-based custom firmware are designed to be more stable than the regular nightly builds, while still allowing users to keep on top of the latest features and improvements.
Right now CM 10.1 M3 builds are available for devices including the U.S. Galaxy S3, international HTC One X, various Galaxy Notes and Galaxy S2s and the current crop of Nexus devices. More are sure to follow in the hours and days ahead, so even if your phone or tablet isn't listed above, it's worth checking the CM download page for more info (or heading to the CM updater if you're using an earlier build).
Source: CyanogenMod Downloads