According to ESRB, this game contains: Blood, Violence
Parents should be advised that MechAssault is centered on violence. Although most of the violence is fairly abstracted, there are exceptions here and there and the overall tone is very grim.
Deaf and Hard of Hearing Gamers should be advised that there are substantial audio cues in the game. Although most of the in-mission ones have accompanying text, and there are handy plot summaries from time to time, it may become hard to follow along.
Gamers with Xbox Live probably have this title already. If they don't, they should look into it. Although MechAssault isn't as complex and quite possibly balanced as more recent games like Return to Castle Wolfenstein, it is a tasty online experience.
Gamers without Xbox Live would best be advised to approach MechAssault with a sense of caution. The offline content is not enough to warrant a full purchase, although it could be a fun rental.