NIS is including extra stuff with the DS version of Rhapsody, in addition to the inevitable Etna/Prinny cameos that will ensure that PS2-era NIS nerds will desire this PS1-era NIS remake. Cornet's trumpet-playing has been expanded into a minigame in which Cornet plays trumpet in the town square to earn Imotium chips from the townspeople. This takes the form of a minigame in which you blow into the microphone in time with an onscreen indicator.
Other new stuff includes a "Kansatsu Notes" feature, in which not only does the game provide a database of information about its characters and monsters, but the main characters offer commentary as well. Dengeki has posted tons of screens of these modes and other parts of Rhapsody.