As of now, only a beta build for PC version is ready to download.
The important part of the update is the option to mix the powers of both available characters. People who prefer to play as Corvo can now eliminate enemies with Emily’s Domino skill etc. You should remember that the patch is in a beta state.
The full version of the update is set to release on December 19th on all platforms. Arkane Studios plans to add a mission selection screen and other difficulty settings in January.