Jonathan Morin the Creative Director at Ubisoft Montreal has revealed on Twitter that Watch Dogs lasts 35-40 Hours to reach the end, but to finish all the missions and jobs is close to 100 Hours.
Watch Dogs coming to PS4, PS3, Xbox One, Xbox 360 and PC in May 27.
@vytla102 I would say the average player which does free roam a bit tend to reach the end within 35-40h. But doing everything is close 100h.
— Jonathan Morin (@Design_Cave) March 15, 2014