Characterizations don't go very deep. Most of the "good guys" are striving to protect a convoy of the uninfected (including children), but they sometimes treat zombie killing as a sport. Villains (besides the ravenous mutated zombies, who can't help themselves) are the remaining authority figures, such as medical scientists (so callous and power-mad they even let their own colleagues get killed) and evil-businessman types -- who are all white males, by the way. That said, the good guys are nicely multicultural.
Frequent carnage inflicted on humans and zombies (including dogs mutated into half-rotten zombies). Impalings, squashings, slashings, burnings, and more; one zombie is pinned by a crossbow bolt, and a crow subsequently pecks out his eye. Humans are bitten by zombies, and countless zombies are shot through the skull. Monstrous tentacles squeeze out a man's eyes. A threat of rape at one point.
Some characters allude to hot dates, but there's no sexual action. Non-sexual female nudity (in the form of clones suspended in fluid sacs in fetal positions) is viewed mainly in profile. One grotesque female zombie has a bare breast.
"S--t" and "bitch" are used, though more at PG-13 levels than R. "A--hole" is a punchline over the closing credits.
Product names visible on computers, cell phones, and vehicles. Ruins of prominent Las Vegas casinos are identifiable. And, of course, there's the fact that the movie is inspired by a popular video game.