Some themes and wallpaper are expected to be included, as well as various sound effects, likely related to the latest film. (digitaltrends.com)
The album also includes various sound effects, as well as the music from the two DLC Packs. (perfectly-nintendo.com)
There's also the various options for gameplay, the Theatre Mode (where you can watch the Music Video for each song, and use various sound effects to simulate the public from a live concert). (perfectly-nintendo.com)