Yannis Mallat, CEO of Ubisoft Montreal & Toronto, said in his announcement that the launch of AC Unity was a highly-anticipated moment for development temas around the world and unfortunately the overall quality of the game was diminished by bugs and technical issues.
How can Yannis apologise to us?
"To show our appreciation for your continued support, we’re making the upcoming Assassin’s Creed Unity Dead Kings DLC free for everyone. For Season Pass holders, we will also offer the choice of one additional game from a selection of Ubisoft titles for free. More details on the offer for Season Pass holders can be found here: AC Unity FAQ."
Season Passes owners can choose a game from these titles (before March 15th 2015):
Far Cry 4
Assassin's Creed Black Flag
Just Dance 2015