If you aren't used to the battle system and don't use Gambits properly/build your characters efficiently on the License Board, it can get tough as newer and more powerful enemies appear as you advance in the story. Some bosses can be very difficult ((SPOILER)Demon Wall >_>), and in addition, the game pulls a FFII and sometimes places superpowerful monsters in places indicating that you aren't supposed to be there yet even though you may have wandered there accidently. Finally, acquiring Gil is rather tedious, as you may have to farm loot by chaining monster kills to sell loot in bulk, which is really the most effective way. I've also had to level up at some points, and of course buy new equipment. But overall it's much more difficult than the recent Final Fantasies.

I'd say it's probably on par with FFT so far, some battles are frustrating, but certainly nothing comparable to

Defeat Wiegraf!
or

Step on the Floodgate Switches!
.