According to the ESRB, this game contains: Mild Language
Parents don't have anything to worry about with either of these games. PaRappa 2 is as clean as they come, and the ESRB's caution of Mild Language in Gitaroo Man was over one use of the word damn. Basically, there's nothing but wholesome stuff here. My only caution would be that younger kids might have significant difficulty with getting down the timing and rhythm required for games of this type. Definitely steer your young ones away from Gitaroo, and you might want to think twice about PaRappa 2 unless your offspring have good manual dexterity.
Gamers in General or Quirky Game Fans owe it to themselves to try out something a little different. If music games are new to you, there is a fair selection available. While I don't really recommend PaRappa 2, the gameplay is as simple as it gets, and is a good starting point for most folks. Rent it, though. Gitaroo Man is by far the better game, but be warned of its substantial difficulty.
Music Game Fans will be disappointed with PaRappa 2's limp soundtrack and shallow offerings. Gitaroo Man is much more substantial and a more worthy addition to the genre.