According to ESRB, this game contains: Mild Lyrics
Parents have nothing to fear from Unison. There is some very mild innuendo in the lyrics, but no language or drug references that I could make out.
Fans of music games would be advised to stick with the PaRappa series or Bust-A-Groove. Both games have better songs and better controls.
Casual gamers will probably find the game bewildering and will likely not have the patience to sit down and put in the necessary time to memorize the songs.
Deaf and Hard of Hearing gamers—although it's strange to say this about a music game – can enjoy Unison. All dialogue during the cutscenes appears in text bubbles, and the gameplay involves repeating visual patterns, which can easily be done without hearing the music. The girls are dancing throughout each stage, so there is always something visually interesting going on that makes up for not being able to hear the music. The only unfortunate thing is that the lyrics of the songs aren't in bubbles.