This one fixes a few bugs in last weeks' build, like the fact that double-the-zombies were being generated most of the time. There was also a multiplayer-specific regression with an exception in general.
Quickstarts are being reorganized and expanded a bit by Strategic Sage. Previously, there was a progressive flow of easier-to-harder for the base game, but the DLC quickstarts weren't really organized in that way. Now they are, alongside other improvements to them.