Actually, it depends on how you set-up your characters but for the most part barring IV, IX, and X, ATB is pretty fast in the rest of the series. Compared to some of the fights in XIII? no, but some of those fights are over so fast its not like I even had a chance to enjoy the spectacle. Yet, fights like the ones against Barthandelus, and some of the bigger Pulse creatures are incredibly long fights, I don't think I ever had a fight with Barty that wasn't over ten minutes long just cause he has HP up in the Yiazmat levels, so while most of the pointless fights are fast, it has its fair share of drudgery fights as well.

As for getting bored with combat, I did, just because every fight was virtually the same. Chain break the enemy juggle him to death. Until later when you fight the big things and it becomes: Make Vanille the lead, summon, spam death. I rarely found myself doing anything differently and watching my party juggle enemies just reminded me of Star Ocean 2 where juggling is pretty much your guaranteed strategy for victory, or the fact this combat system is pretty much Xenosaga Episode 2's combat system (though in X2 you can also smash enemies into the ground and combo additional smashes) so its not like I can't get this fix from other games that predate it, sometimes almost by ten years, but with the added bonus of having control over my party. I'm not even going to get into how much this game recycles enemy types. Juggling Behemoths does lose its luster when they are regular mooks that show up every other dungeon.

As for the enemy system, they are actually your third party member from what I've gathered, each one being specifically designed for a paradigm role. I'm thinking its something like having a Behemoth as a Commando, a Goo monster as a Ravager, or a Machine as a Sentinel. At least that is my understanding, so its not so much a summon system as much as its paradigm shifting with your monster determined by what you need your third Role to be. I'm more concerned to see if any of the returning cast will be playable besides Lightning, cause this system pretty much sets up all you need for a three man band.