Well, the difficulty depends on how much free time you have for it. It'll get harder if you don't have time for it, obviously. In general, Music Stars aren't needy, they're just hard work. You have to practice with their band to pass Pro Debut later on, make sure you have enough money to buy food, play games to get its Skill Points up, yadayada. Not to mention keeping their stress meter down
To keep it down, you can either play a game, praise it, give it food if it's hungry, or give it its toy. So yes, if you're a busy person the Music Star will be a hard little bundle of joy to deal with, but if you pay attention to it, it'll be a breeze.
Edit: I'm not giving it a rating because it differs from person to person :I
Edited by KeroPyontchi, 07 April 2013 - 01:15 PM.