Yes. I enjoyed the game and beat it a month or two ago. It's a bit like GTA-meets-Deus-Ex in gameplay, being an open world based in/on a city (Chicago) with a lighter focus on driving dynamics, though there is a decent mix of vehicles loosely based on real cars or mashups of real cars.
The main story arc is well-written and executed, though if you read reviews there are a lot of complaints about Aiden. Personally, I think his portrayal fits given the backstory - you really can't expect a "fixer" to be likeable or relatable (and Jordi is there for the entertainment value), but he does open up a little as the story progresses. The voice acting and story are good enough that you could string together a watchable action flick from the cutscenes; it isnt groundbreaking, but it is entertaining enough. The various factions and individuals you encounter and expose in Chicago, from corrupt politicians and businessmen to low level gang members, hitmen and hackers, makes the bigger, unfolding story fairly compelling. The "morally grey protagonist trying to save his family" is old hat, but perfectly fine as a motivator and setup for the larger plot.
The "hacking" elements are pretty unrealistic depictions of hacking, but they make for easy puzzles and make NPCs a little more interesting than your average game. The footage and conversations you observe in game from hacking servers and computers raise excellent moral and philosophical issues - as does the whole concept of putting an entire city's infrastructure onto a single network - though. The conversations you overhear through cybersnooping brings home the creepiness factor and reality that essentially everyone in the modern world is a carrying around the ultimate bug...
Jumping from camera to camera to unlock doors does get old after a while, but it is a better puzzle system than some modern, open-world games.
I'm pretty mixed about the online multiplayer hacking and fixer contracts because they can be frustrating and boring at the same time. One mode is basically hacker hide and seek, which apparently I suck at, so YMMV.
I love the mini games (basically augmented reality within the game) though. Worth $15 just for them. The Space Invaders one (NVZN) is my favorite.
No complaints about the combat system itself, but I did feel like there weren't enough new weapons by the middle of the game, or interesting store inventory. At a certain point I didn't bother hacking into people's bank accounts for money because there wasn't really anything left I could upgrade to in weapons or vehicles. The game as a whole was relatively easy as well. The only troublesome parts for me were where you have to direct other characters using cameras (but really it was only one of those that was annoying, and it didn't happen often). Between the sniper rifles and the grenade launcher even the tougher battles (and there is one particular "boss" who could be hard otherwise) were pretty easy.
The score is fitting but not particularly memorable... it matches the mood and atmosphere of the game and is timed well, but offhand you couldn't get me to recall any of it. It's atmospheric but not catchy. The soundtrack on the other hand is a bit random and doesn't have as many standout tracks as the GTA series. I did enjoy hearing "Feds Watching" play every so often while driving, though.
I would give the game an 8/10 overall. The combat and gameplay feels like an older GTA (pre GTA V) game with hacking elements thrown in. The main story is good, though some of it is fairly well-trodden territory, besides the ctOS bits which feels a little fresher than the generic main enemy, who was a let down. Other characters like Bedbug, Jordi, and Iraq were less cookie cutter.
I hope there is a sequel. Without giving anything away, the past and future of Aiden feel a bit unfinished to me. There is definitely room to make this a series. If they add to the hacking abilities - the smartphone as a weapon was the biggest innovation from this game - and make the cars less arcade-y like huskystafford points out below, the next game could be a no-brainer, game of the year contender. Watch Dogs is a good game, but I did have my expectations set a little too high because of the initial hype leading up to the game.
Still, waiting a full year to play it means I didn't experience any bugs and had time to temper my expectations and could pay less to buy it. Excellent value if you can get it for $15... and even if it were selling for twice that I would still recommend buying it.