I'd say it's more of an Assassin's Creed in a GTA setting. Might seem like a strange comparison, but the hacking introduces a stealth element. While running and gunning is an option, you can also stay in cover, hack an explosion near an enemy, or even hack their grenades (which sometimes they'll try to throw it away from themselves). Not to mention the Ctos towers which act as AC's viewpoints.
Also, I'd say trying to play a more gunning style is a little more difficult as opposed to GTA, but that could be because I don't have much in the way of weaponry just yet being near the beginning. Running from cops is a bit harder in this game as well. GTA was too easy with their little vision cones, but the scope for WD cops is a bit ridiculous and without a good car you could struggle a bit trying to make your escape. That said, before the cops come, you do have a sizeable warning to get out of the area before they show up so it is easier at the same time.
Can't comment on the story much since even though I've played for probably six hours at this point, only did maybe five missions. Between the digital mini games (Spider Tank, Coin Rush, Etc.), random side missions such as fixer contracts, or even just walking around profiling everyone you meet (which is strangely addicting), there's a good bit to do. Also the online element is a lot of fun, trying to hack into other people's games and not being noticed. Which goes wrong for me more times than not.