Note: This is a review of the Funimation English dub of this series.

Violence / Gore:
C-Control contains many fight scenes in which characters/creatures are injured and bleed black blood. Sometimes the scenes are mild, other times more graphic (at one point a disembodied arm is shown). There is often black blood running down a character's face, and sometimes pools/spurts of black blood when a character is injured. As the fights take place in an alternate dimension (sort of), the characters are healed shortly after as if their injuries never happened.
In the real world, a man purposefully jumps in front of a train. Another man tries to jump off a building. A creature's face cracks open to reveal claws.

Nudity / Sexual Content:
The torso is shown of a girl taking a shower. This is quite detailed. After, the girl is shown putting on her underwear/bra (this scene is more mild).
The top of one character's bra is often seen peeking out of her shirt.
A woman jumps into a vehicle on top of a guy. She's flat on top of him during an entire conversation. She finally moves and the guy gasps because he had been unable to breathe since her chest had been covering his face.
One character wears a very short skirt, but she wears tight shorts underneath it which does provide some coverage.

Potentially problematic theological themes:
The Financial District of C - Control initially seems evil. It's common to see three 6's on credit cards, time counters, etc. in the district. The district is often shown as a dark place, and the "deals" solidify that when they turn violent. That said, the spokesperson for the Financial District says that he gets his orders from "the man upstairs." He later says that he "follows orders from above."
In the end, the district is not shown to be necessarily good or evil. It depends(largely) on the people in the district.
Characters put up their "future" as collateral for vast amounts of money. Not to mention that (in the district) when someone gets hurt, black money often spews out of them. Also, the Financial District seems to have the power to erase humanity from existence.
Many Assets are personified as monsters.

Other potentially problematic themes:
Mild swearing - a** and b**** are used most commonly. Averages about 2 swears per episode.

* The love of money is the root of all evil. C- Control does not deny this. The power and influence of money depends on the user. Some try to do harm while others try to do good. What's more important: having a future, or having money?
In the end, this anime finishes with quite a few questions unanswered. Not entirely an action series, [C] focuses a lot on how out of control money can become. Still plenty of fighting to keep audiences entertained. Certainly a unique anime. Side note: I really enjoyed the character art.