The FF Wiki reveals that defeating each episode will unlock a new job. The jobs are Freelancer (default), Warrior, Thief, Monk, Red Mage, White Mage, Black Mage, and Summoner.

I should hope that Freelancers are strong enough and don't need abilities from other jobs to be strong. Otherwise, going through your very first episode just to unlock one job only using Freelancers would really suck. Also, I hope each episode isn't that expensive. That would sure suck paying a lot of real money just to have all of the jobs available, when practically every Final Fantasy gives you all the jobs within the game without any additional cost.

Also, anyone think that one or more of the characters in this game will be in Dissidia Duodecim?