A great open beautiful world with lots of things to see and to do !
In short: WD2 is a combination of GTA and Saints Row. It is funnier than GTA but more realistic and serious than Saints Row. Which is great to enjoy !

The story of the WD2 is more hipster, funnier, swagger compare to the first Watch Dogs.
The story can be considered as 2 parts.
The first half of the game (The Slow part) is about wrecking havoc to the systems, chill out with friends, harassing other people and have fun. Yes, because it is about Marcus (The main character) and his friends having fun being hackers, it's usually slow pace and unfocus. But it's important because it introduce you to the world and the people around you, so be patient and enjoy the party with Marcus and his fellas because most of the missions are fun to play !
Then, the second half of the game (The Fast and Serious (And also Furious) part) is about Marcus and his gang take down the "Bad guy" for good. This part of the game is where things get serious and it feels like GTA. Many factions (The gangs, the police, the EVERYTHING in the game) having conflict with each other. The story at this point become faster, hotter and more interesting, more serious, more action ! It helps build up the climax the game needed to the end game.

Beside, the side missions are very interesting and various. Most of them give you good laugh !

"Creative" is what the gameplay of WD2 is.
It has Shooting, Stealth, Hacking, RPG, Customization and Exploration.
Stealth: Combine with Hacking make tons of possibilities in gameplay and super fun ! (The enemies AI in stealth section is somewhat dumb, but it's not bad anyway, because sometimes their hallarious reaction make we laugh !).
Hacking: This is where the game shine and your creativity come to play ! From controlling enemies cars to giving them false criminal infomation status to make the police come and arrest them ? Sometimes you can clear the entire enemy camp without wasting a bullet or even set foot into their territory. This is the proof that "A mind sharper than any blade" is true.
But what if your plan fail ? Then the Shooting come to play !
Shooting: The game's cover-shooter TPS formula feel very smooth and responsive. You can still Hacking while shooting to make total mayhem ! So if you bored being silent, make some noise !
RPG WD2 has a level up system that allows you to obtain new skills that make big change in the gameplay.
Customization While you can customize your characters, weapons and vehicle (Only the appearance) it feel a little shallow, I wish we can have more customization option in the base game not in DLCs ...
Exploration: The game has many "Place of Interest" for you to explore and yes, they are all interesting because the world is so living, random NPC, the places, ... all are so detailed. For example you can see each NPC's job, their income, status, even the conversation they are in or the message they are texting.

Multiplayers: The game put other players randomly into your game while you are freeroam (It is disable when you are in mission or you can disable this function yourself in setting). Both co-op and PVP are fun to play.
Driving: Driving is smooth and can be creative with Hacking. The pursuit (Wanted level like in GTA) is hard but when you understand it's mechanic, it becomes easier.

Music in WD2 is soooo great.

Voice acting helps bring the characters to life and add much of personality to the characters.

WD2 is an exllenct alternative for GTA and Saints Row, it is good to start in Watch Dogs series if you haven't played any Watch Dogs because you don't need to play the first game to understand the story of WD2.