In preparation for tomorrows Episode 4 launch, we've just pushed a new patch to Steam.
Episode 1 only users will have roughly a 90MB download.
When Episode 4 becomes available at 00:01 UTC:
2.4GB download for Episode 4
Specific issues addressed in Episode 1 patch:
Preparation for Episode 4.
Improved stability for users in certains areas of the game.
Auto resize text display for item descriptions so it always fit the screen.

Update - 20150729
Fix for crashing on launching episodes on some audio setups.

It includes all fixes in previous patch