Wanting to chime in: Having played up to about I would say half of the game, maybe a bit more, this game is incredible. For me Ubisoft is mostly hit or miss, but they really have something special with Watch_Dogs. The game looks very good most of the time, the action is tight and makes you feel like a badass, the UI isn't convoluted despite the amount of contextual interactions you have, the guns feel good, the stealth is solid, the movement is fluid (it seems as if instead of adding in a generic "climb", they actually worked to design every piece of the world to be moved across in a satisfying way) and the Story is good with some interesting characters despite having some flaws.
It's Splinter Cell mixed with AssCreed, GTA and some Saints Row hooligan stuff tied together with a Jason Bourne/James Bond plot and story arc. Fantastic.