According to ESRB, this game contains: Fantasy Violence, Language, Suggestive Themes
Parents don't have much to worry about despite what the ESRB says. Besides some of the female (I think they were female) characters sporting some mildly revealing clothing, there's not much of anything going on here. The story makes no sense at all, the violence is nothing but robots shooting each other with ten million bullets each, and I have no idea what they were seeing when they called out "suggestive themes." I doubt any kid would want to play this game in the first place, so don't stress.
Shooter fans may want to check it out just for the sheer oddity value, but wait until it's $5 in a bargain bin, because that's where it's going to be. Too simple and shallow, it's kind of an interesting idea that didn't go anywhere. Your money is better off buying either a fighter or a shooter, because this game attempting to meld both genres just fails.
Deaf and Hard of Hearing Gamers won't have any problems. Voiceovers are accompanied by on-screen text, and there are no significant auditory cues during gameplay. It's all visual.