During a livestream event being held right now by Ubisoft, Watch_Dogs Creative Director Jonathan Morin explained that the game will have quite a few elements we’re familiar with in open world games.
You can collect cars by hacking people and stealing their identity and in other ways, and then you can call the “on demand” during free roaming in order to have them delivered to you. On the other hand you can’t customize them.
The game also has “tons” of costumes and many minigames like chess or poker, included some that the team still isn’t ready to talk about.
There are also many kinds of guns, from automatic to suppressed guns, also including grenade launchers.
On the other hand there are no flying vehicles like planes and helicopters, because they’ve been done already and the game’s world doesn’t have the kind of scale that makes them really enjoyable, so the development team preferred to focus resources on things players haven’t seen before.