According to ESRB, this game contains: Blood and Gore, Language, Violence
Parents don't have much to worry about. The game is all about killing aliens and big bugs with weaponry. The violence is not very graphic, and there's no real gore to speak of. Be aware that experimenting with weaponry is a large element, so parents who don't want children to access games that place guns, swords, and really, really big hammers in the spotlight should stay away.
Dungeon crawl fans may want to check the game out. It does a great job of having a very wide range of weaponry and armor, but the action is dull and repetitive, even for this genre. Level design is very simplistic, and the story is utterly forgettable. Leveling up isn't handled very well, with bonuses and improvements being mostly negligible. It seems like all the elements are here, but it never comes together.
PSP gamers hungry for another piece to show off to friends will likely be wowed by the high production values and good looks, but most players will likely be bored of the one-note action within an hour or two. There are better projects to spend your money on.
Deaf and Hard of Hearing gamers will have no problems. There is no speech in the game, all dialogue happens via text on screen. There map during gameplay is a great visual aid, and there are no significant auditory cues during combat. It might be boring as hell, but it is fully accessible for people with hearing disabilities.