According to a post from the official forums, even though just one percent of the Grand Theft Auto IV owners are affected by the problems, this patch will solve them. Here are some of the fixes to be made by this patch:
– A fix to the crash after legal screen that some German customers were reporting.
– Numerous improvements to the video editor: Smarter naming of videos, improved rendering quality, better fx during replays
– Fix to bowling while using certain sensitive mice
– Fix for ATI 1900 shadows
– Overall savings to memory
– Graphic improvements to particle systems and mirrors
– Multiplayer character settings are preserved
– Support for DirectInput controllers. Note: The current hack way of supporting these controllers may not work with the improved functionality. So we recommend you remove the hack before upgrading to the patch.
For the full list of changes, visit the official GTA IV boards.