Heck, the whole game is pretty hard--and certainly so on the first run-through. If you know what you're doing I'm guessing you could get through relatively unscathed, but it's definitely the type of game where if you make a mistake you can get hurt bad (ie try casting Holy against a Behemoth) no matter what level you're at.

I defeated Zeromus last night for the first time, and even with levels in the high 70s, the battle was pretty intense. For the amount of relatively mindless leveling the game encouraged, at least the payoff in terms of the story, final level, and final battle, made it worth it.

FFIV = Double Plus Good