In reading the reviews there is a lot of criticism about the game structure.
You mentioned not being able to gain experience of do much with your characters. This will last for the first 20+ hours of the game. It isn't until much later that the game unlocks everything and actually lets you play it fully with full battle control and character experience, levelling and customisation.
However the reviews I've read said it is well worth getting through the first part as once you get to the fully unlocked system the combat is the best seen in any FF game to date and is something very special.