It is basically GTA, but more bonkers, as a matter of fact, I like this one more over GTA IV, it has a Vice City vibe to it, and we all know VC was the best GTA, you got a character creator to make your own protagonist, a wide variety of missions, some of them are very impactful (loved the cinematic flare of the graveyard mission), the weapons are punchy, the vehicles handle pretty well (fuck helicopters tho). in game the violence is gratuitios and over the top. but they evade any gory close ups in cinematics.
Side activities can get repetitive, but they are fun for the most part (again, fuck helicopters), and reward you with some seriously broken upgrades like infinite ammo for some weapons and infinite stamina
All is not perfect, the physics engine can be wonky at times, bringing to teh table the worst enemy of sport cars: sidewalks. Also, in cinematics object tend to float around, specially when characters are "holding" tehm with their hands. And the game crashed multiple times, curiously enough, it happened most of the times when I was entering a car.
Still, great game, had a lot of fun, highlly recommend it for sandbox fans, just save often, and don't worry about grabbing all the collectables, just enjoy the ride.