I feel ALTTP is harder than Majoras Mask, though ALTTP truly is not that hard. Younger gamers have just grown accustomed to very guided games and aren't used to the still guided style of ALTTP.
Anyways, the first time I played Majoras Mask I found it very difficult, though that may have been because I was 9. Just manage your time well, pay attention to highlighted words in text boxes, and if you're confused in a dungeon, take a minute to stop, look at the map, and think about what you ned to do, where you need to go, and what you might need to do so.
Also, bring a fairy or two when you fight the third boss for the first time.