Prototype 2's visual improvements over the original might not become apparent until you're a few hours into the game. If you don't remember, Prototype's vision of Manhattan looked decent, but relatively devoid of color. Browns and reds pervaded the entire game no matter where you went. Prototype 2 is more colorful. The greens are greener, the blues are bluer, and the reds are... well, brighter. I didn't think it possible, but Prototype 2 is more violent than the original. The first one saw thousands of civilians, troops, and mutants eviscerated in horrifying, disgusting ways. This one goes to eleven in that regard. It takes its time grossing you out; one finishing move has an enemy slowly split in two down the middle. Another results in an enemy's upper half stretching a few feet away from his/her lower half -- but the two halves remain connected by a disgustingly elastic bit of human tissue. The animation work is largely the same as it was in 2009; we may have a new protagonist, but his movements are identical to Alex Mercer's. The only drawback is that the framerate isn't as good this time around.
Prototype 2's voice acting is solid, though Barry Pepper does not return to reprise his role as Alex Mercer. The replacement voice sounds absolutely nothing like Pepper, but since Mercer isn't the focus of this game, it's okay. James Heller's voice is essentially the stereotypical vengeful black guy with an attitude, but he's still a lot of fun to listen to. Some of the insults he hurls are laugh out loud funny; one particular instance during the final boss fight made me spit out my coffee. Every Blackwatch soldier is a font of ignorance and trash talk, and you'll be more than happy to snack on them. The soundtrack doesn't borrow any of the motifs from the original Prototype, but it's still appropriate stuff for a power fantasy.