According to ESRB, this game contains: Violence
Parents shouldn't have any concerns about Phantasy Star Collection's content. They should be worried about the difficulty, which will leave most younger gamers incredibly frustrated.
Hardcore RPG fans will no doubt like the package despite the fact that the games haven't aged particularly well. These were classics back in the day, and they retain enough of their original charm to make adding them to your collection worthwhile.
Casual gamers and modern era RPG fans will most likely be disappointed. The lack of upgrades to the games (they're direct ports of the originals) makes it so the games look fairly antiquated by today's standards. Plus, the onus on extreme power leveling to the exclusion of everything else (including narrative) will turn off a lot of players.
Deaf and Hard of Hearing gamers have nothing to fear—there's no spoken dialogue in the game at all, and the music just doesn't sound as good as it did on the original cartridge versions anyway.