Famitsu, via Siliconera translation, claims that the map-making functionality of Etrian Odyssey will make an appearance in Persona Q. This gives prospective dungeon crawlers the chance to sketch out a map of their virtual surroundings using the 3DS' touchscreen. It's unknown how big a role this feature will play in Persona Q, though in the Etrian Odyssey games it was just shy of mandatory for anyone hoping to make any real progress.
Likewise, Persona Q will feature FOE encounters. Officially, "FOE" is an acronym for "Formido Oppugnatura Exsequens," but more pragmatically you can think of these FOEs as largely optional boss encounters. Killing a FOE results in great rewards, but more often than not, it will be in a player's best interest to flee from the battle until properly prepared for that specific fight.
Persona Q: Shadow of the Labyrinth lacks a specific release date, but Atlus has targeted the Fall of 2014 to launch the handheld roleplaying epic.