This game is absolutely addicting, I bought it the day it came out and barely taken a breather. And you use Ad Hoc to play your friends, you have to be within 20 yards within each other, I think..
But there's a lot you can do on this game, I've logged over 200 hours and still haven't completed it.
The game is pretty much like any other FF, except you have to buy your characters (including Shantotto and Gabranth), but the level system is the same and you can edit your character's equipment. The battle system is a bit confusing at first, but you get used to it eventually.
If you have the money, I'd suggest getting Dissidia, it's well worth it.