I found Watchdogs to be a decent, yet fairly unremarkable game. The profiler and hacking civilians for secrets was little more than a line of text or audio log randomly assigned, I found myself missing some of the smaller details that you would find in the more recent GTA games, like civilians trying to take back stolen cars, or fighting the player when another civilian is attacked.
Watchdog cops were absolutely abysmal. Stealing a car would get half a dozen cops on me, but running down ten civilians and causing thousands of dollars of damage wouldn't go noticed? I don't remember seeing any cops on the water, the helicopter AI could not be more annoying (sit right on top of me in a position where my camera can't rotate to see unless I aim, slowing me down for the sniper) and apparently they'll fight against you alongside gangsters - not what they game says they'll do. There is also a lack of variety in the police chases, as it seems to be either a couple of cars, or a few more cars and a chopper.
The novelty of the multiplayer wore off pretty quick. There seemed to be a lack of significant progression for completing matches, and unless I'm missing something the free roam lacked activities aside from fighting the police. Unfortunately the police only seem to target one player at a time, focusing all fire on a single poor bastard while leaving his five friends to waltz around the battlefield mowing them down like the sitting ducks they are.
I found the story to be engaging. Don't expect anything new or spectacular, but it does what it does fairly well.
The AI and missions were fairly decent. They AI was smart, trying to flank you when they could and firing on your last known location when you broke line of sight. Stealth was passable but shallow. Being unable to move bodies boiled it down to blowing up as many enemies as possible using cameras and hacks before charging in with the silenced pistol and taking them all down before they got a lock on you. Most missions and activities were more open ended than those in GTA IV, but not by much.
PC port was also atrocious, and even on ultra the graphics did not live up to the previews.
I would have appreciated more depth to the hacking system (no, I don't mean minigames) and better fast travel (like the taxis in GTA), but despite my gripes I still enjoyed it. It doesn't do anything new, but what it does it does fairly well.