According to ESRB, this game contains: Violence
Parents probably won't have much problem with Metroid Prime. There is plenty of violence, but it is only against odd space creatures, and, while intense, it's never notably gory.
Fans of the original Metroid and its sequels should definitely check this out, assuming they don't have an irrational aversion to first-person games. It is easily the best, most engaging game of the series on every possible level.
Fans of Nintendo's star franchises like Mario and Zelda might also want to check this out, since it has that same sense of magic and inspiration as Miyamoto's best work.
Fans of first-person shooters might enjoy how Metroid Prime excellently incorporates elements of the genre into its own unique experience, but those looking for something along the lines of Halo or Unreal Tournament should probably stay away.
Fans of atmospheric action/adventure games like System Shock or even Resident Evil might really appreciate Prime's occasionally powerful sense of tension and fear as well as its mysterious plot.
However, it should be mentioned that Prime's main plot-twist actually depends somewhat on its sister game for GBA, Metroid Fusion. I'd recommend at least playing Fusion right before or right after Prime since the perspective it lends will make the end of Prime a lot more meaningful.
