Battles ostensibly play themselves for you, mostly because Square Enix's new Paradigm System is so contrived and complicated that the player would be confused if he had to control it himself. Instead of manually inputting commands for all your characters, everybody -- including the player's character -- can automatically fight of their own free will.
However, the new system also relies too heavily on trial-and-error, and players can expect to die a few times before nailing how certain enemies work. This is especially true of the Eidolon battles, that rank easily among some of the worst RPG boss fights in history. Players have a time limit in which to learn and then perform the various actions each Eidolon wants you to do. The first time you fight each Eidolon, you'll essentially be going through a practice run as you learn how to fight it before dying an irritating death. Square Enix even knows that its battle system is trial and error, since it gives you the option to retry fights at any point during combat, or after death.
The only truly interactive and intriguing part of the battle is Eidolon summoning, but wouldn't you know, they're all pretty much useless. Despite being able to perform a variety of visually stunning attacks, Eidolons do barely any damage to the enemy, and the Stagger meter empties as soon as they disappear, meaning they can come and go without contributing anything to the battle.
There are no distractions from the main quest (and boy were distractions needed) until thirty hours into the game, and by that point it's a case of too little, too late... Even the famous Chocobo theme, brief though its appearance is, has been ruined with some ill-advised and embarrassing vocals.