Why I am currently playing Watch Dogs
Open World – Check
Deep Single Player Campaign – Check
Side missions out the wazoo – Check
Multiplayer – Check [you can race and/or hack]
On my PC gaming rig, I have seen some very minor optimization issues. [none of which have taken away from the fun factor] Overall, I am very content with this game. I can either play for just a couple of quick minutes via side missions. [like chess, poker, shell game, etc] of which all go towards unlocking weapons, vehicles and other achievements. Then when I got more than just a few minutes, I can challenge a gang hang out, a criminal convoy or the main story.
So, you are not just running around hacking people and stuff with your smart phone, but it is a part of the game.