FoF isn't your typical card draw spell, which has been reprinted many times already. It's an entire strategy packed into a single piece of cardboard.
This card can be just as good in Limited as it is in Constructed, as you get to choose which pile to put in your hand, and that is something your opponent can never guess.
Basically, it has no drawbacks, and having an instant speed makes a perfect preparation for your next turn. That's where the good ol' "EOTFOFYL!" phrase stems from. (End of turn, Fact or Fiction, you lose!)