According to ESRB, this game contains: Mild Language, Violence
Parents have nothing to worry about, although I doubt that very many younger children will select this game in the first place. Since all combat takes place between robotic machines, there is no blood, gore or graphic violence. Similarly, there is absolutely no sexual content and no significant questionable language. It's as clean as a game about warfare can be, almost to the point of being a little bit sterile.
Armored Core addicts will definitely see the connection with Hounds that are customizable from the ground up, just like FromSoft's other franchise. However, be aware that there aren't as many options and construction is a little bit more limited. Additionally, the majority of parts for customization are only available online, and must be purchased with money that is earned from online battles.
Solo players should be aware that the majority of the game's content is dedicated towards online multiplayer. The training missions are interesting and enjoyable, especially in the way that each "role" functions differently than the others, but there's not enough content here to call the single player mode an actual "game" all by itself. There are ten additional single player missions available online, but they're all straightforward "kill" missions that aren't very interesting.
Multiplayer fanatics will be treated to a game that is made especially for them, although it's not nearly as fast or blood-soaked as some might want. The pace is a lot slower and requires a high degree of teamwork and strategic planning, so jumping on late at night for an impromptu "quick game" probably wouldn't be a very fun thing.
Deaf and Hard of Hearing gamers will have access to the single player story mode since the dialogue comes with subtitles, but being able to hear gunfire and explosions on the battlefield is helpful. Additionally, people with hearing impairment will be at a disadvantage during any online play since communication will be more difficult, if not impossible. Definitely try before you buy.