Nichts ist perfekt. Auch neu veröffentlichte Spiele benötigen von Anfang an einen Patch. Nach knapp einer Woche ist für Assasin's Creed Unity der zweite Patch erschienen und ein dritter ist schon in Arbeit.
Seitens Ubisoft hat man schon ein paar Details verraten, was der Patch ausbessern soll.

Hier der originale Kommentar:

Gameplay: this includes bugs like Arno getting stuck on certain areas of the map (including a few more hay carts), problems with getting into/out of cover, character animation bugs, and general camera problems

AI & Crowd: in this category are problems with NPC animations, crowd events, and crowd stations, NPC navigation issues, as well as bugs related to NPCs detecting Arno’s activities in various situations

Matchmaking & Connectivity: this covers a number of issues related to co-op play, including bugs with joining games in-progress and problems that happen during host migration

Menus & HUD: fixes in this category will address missing details in certain menus, problems with some of the mission objective and co-op update pop-ups, localization inconsistencies, as well as some of the issues with menus and pop-ups overlapping each other

General Stability: this includes fixes for a number of crash situations we've identified in both campaign and co-op modes.