According to the changelogs, there will be two patches (the second patch may be released after the game's launch). Far Cry 4 releases next week, and you can view the complete changelogs of these two PC updates below.

Far Cry 4 v1.2.0

Added ability to change FOV scaling.
Added nVidia GeForce Experience support.
Fixed various controls issues
Fixed various Graphic issues
Fixed various IGE issues
Fixed various Multi-GPU issues
Fixed various Multi-Monitor issues
Fixed various UI issues
Playing a map from Map Browser two times now don’t trigger an Error.
Skills, Crafting and Progress Menu now cannot be accessed while playing a created map. 

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Far Cry 4 v1.1.0

Fixed crash in IGE.
Fixed an issue with incorrect characters in map naming.
Fixed screen tearing when performing a handgun takedown.
Fixed various controls issues
Fixed various Graphic issues
Fixed various IGE issues
Fixed various localization issues
Fixed various Multi-GPU issues
Fixed various Multi-Monitor issues
Fixed various multiplayer issues
Fixed various sound issues
Fixed various UI issues
Fixed various Uplay Actions issues
Fixed various Uplay Rewards issues
Saved maps from IGE and Downloaded now can be opened in the Editor from in-game.
Skills, Crafting and Progress Menu now cannot be accessed in Arena.
The game now boot if the game folder name contains Cyrillic characters.
The game now boot on Korean localization.